nixos/manual: strip un-MD-able tags

productname, application, acronym, guilabel, and guibutton were so far
not rendered specially and can go away completely.

replaceable does render differently, but since it was only used twice
and in places where the intent should be clear without the extra markup
it can go as well.

nixos/modules/services/editors/emacs.xml

@@ -20,20 +20,20 @@
  <para>
   Emacs runs within a graphical desktop environment using the X Window System,
   but works equally well on a text terminal. Under
-  <productname>macOS</productname>, a "Mac port" edition is available, which
+  macOS, a "Mac port" edition is available, which
   uses Apple's native GUI frameworks.
  </para>
  <para>
-  <productname>Nixpkgs</productname> provides a superior environment for
-  running <application>Emacs</application>. It's simple to create custom builds
+  Nixpkgs provides a superior environment for
+  running Emacs. It's simple to create custom builds
   by overriding the default packages. Chaotic collections of Emacs Lisp code
   and extensions can be brought under control using declarative package
-  management. <productname>NixOS</productname> even provides a
+  management. NixOS even provides a
   <command>systemd</command> user service for automatically starting the Emacs
   daemon.
  </para>
  <section xml:id="module-services-emacs-installing">
-  <title>Installing <application>Emacs</application></title>
+  <title>Installing Emacs</title>
 
   <para>
    Emacs can be installed in the normal way for Nix (see
@@ -45,7 +45,7 @@
    <title>The Different Releases of Emacs</title>
 
    <para>
-    <productname>Nixpkgs</productname> defines several basic Emacs packages.
+    Nixpkgs defines several basic Emacs packages.
     The following are attributes belonging to the <varname>pkgs</varname> set:
     <variablelist>
      <varlistentry>
@@ -115,8 +115,8 @@
     (<filename>package.el</filename>) from
     <link
         xlink:href="https://elpa.gnu.org/">Emacs Lisp Package Archive
-    (<acronym>ELPA</acronym>)</link>,
-    <link xlink:href="https://melpa.org/"><acronym>MELPA</acronym></link>,
+    (ELPA)</link>,
+    <link xlink:href="https://melpa.org/">MELPA</link>,
     <link xlink:href="https://stable.melpa.org/">MELPA Stable</link>, and
     <link xlink:href="http://orgmode.org/elpa.html">Org ELPA</link>. Nixpkgs is
     regularly updated to mirror all these archives.
@@ -357,7 +357,7 @@ in [...]
   <title>Running Emacs as a Service</title>
 
   <para>
-   <productname>NixOS</productname> provides an optional
+   NixOS provides an optional
    <command>systemd</command> service which launches
    <link xlink:href="https://www.gnu.org/software/emacs/manual/html_node/emacs/Emacs-Server.html">
    Emacs daemon </link> with the user's login session.

nixos/modules/services/matrix/synapse.xml

@@ -167,8 +167,8 @@ in {
    and have rebuilt NixOS:
 <screen>
 <prompt>$ </prompt>nix-shell -p matrix-synapse
-<prompt>$ </prompt>register_new_matrix_user -k <replaceable>your-registration-shared-secret</replaceable> http://localhost:8008
-<prompt>New user localpart: </prompt><replaceable>your-username</replaceable>
+<prompt>$ </prompt>register_new_matrix_user -k your-registration-shared-secret http://localhost:8008
+<prompt>New user localpart: </prompt>your-username
 <prompt>Password:</prompt>
 <prompt>Confirm password:</prompt>
 <prompt>Make admin [no]:</prompt>

nixos/modules/services/web-apps/discourse.xml

@@ -68,8 +68,8 @@ services.discourse = {
  <section xml:id="module-services-discourse-database">
    <title>Database access</title>
    <para>
-     <productname>Discourse</productname> uses
-     <productname>PostgreSQL</productname> to store most of its
+     Discourse uses
+     PostgreSQL to store most of its
      data. A database will automatically be enabled and a database
      and role created unless <xref
      linkend="opt-services.discourse.database.host" /> is changed from
@@ -94,9 +94,9 @@ services.discourse = {
    <title>Email</title>
    <para>
      In addition to the basic setup, you'll want to configure an SMTP
-     server <productname>Discourse</productname> can use to send user
+     server Discourse can use to send user
      registration and password reset emails, among others. You can
-     also optionally let <productname>Discourse</productname> receive
+     also optionally let Discourse receive
      email, which enables people to reply to threads and conversations
      via email.
    </para>
@@ -159,7 +159,7 @@ services.discourse = {
    <title>Additional settings</title>
    <para>
      Additional site settings and backend settings, for which no
-     explicit <productname>NixOS</productname> options are provided,
+     explicit NixOS options are provided,
      can be set in <xref linkend="opt-services.discourse.siteSettings" /> and
      <xref linkend="opt-services.discourse.backendSettings" /> respectively.
    </para>
@@ -168,7 +168,7 @@ services.discourse = {
      <title>Site settings</title>
      <para>
        "Site settings" are the settings that can be
-       changed through the <productname>Discourse</productname>
+       changed through the Discourse
        UI. Their <emphasis>default</emphasis> values can be set using
        <xref linkend="opt-services.discourse.siteSettings" />.
      </para>
@@ -205,8 +205,8 @@ services.discourse = {
      <title>Example</title>
      <para>
        The following example sets the title and description of the
-       <productname>Discourse</productname> instance and enables
-       <productname>GitHub</productname> login in the site settings,
+       Discourse instance and enables
+       GitHub login in the site settings,
        and changes a few request limits in the backend settings:
 <programlisting>
 services.discourse = {
@@ -260,7 +260,7 @@ services.discourse = {
   <section xml:id="module-services-discourse-plugins">
     <title>Plugins</title>
     <para>
-      You can install <productname>Discourse</productname> plugins
+      You can install Discourse plugins
       using the <xref linkend="opt-services.discourse.plugins" />
       option. Pre-packaged plugins are provided in
       <literal>&lt;your_discourse_package_here&gt;.plugins</literal>. If

nixos/modules/services/web-apps/keycloak.xml

@@ -29,7 +29,7 @@
        Refer to the <link
        xlink:href="https://www.keycloak.org/docs/latest/server_admin/index.html">
        Keycloak Server Administration Guide</link> for information on
-       how to administer your <productname>Keycloak</productname>
+       how to administer your Keycloak
        instance.
      </para>
    </section>
@@ -37,10 +37,10 @@
    <section xml:id="module-services-keycloak-database">
      <title>Database access</title>
      <para>
-       <productname>Keycloak</productname> can be used with either
-       <productname>PostgreSQL</productname>,
-       <productname>MariaDB</productname> or
-       <productname>MySQL</productname>. Which one is used can be
+       Keycloak can be used with either
+       PostgreSQL,
+       MariaDB or
+       MySQL. Which one is used can be
        configured in <xref
        linkend="opt-services.keycloak.database.type" />. The selected
        database will automatically be enabled and a database and role
@@ -103,7 +103,7 @@
        <xref linkend="opt-services.keycloak.settings.hostname-strict-backchannel" />
        determines whether Keycloak should force all requests to go
        through the frontend URL. By default,
-       <productname>Keycloak</productname> allows backend requests to
+       Keycloak allows backend requests to
        instead use its local hostname or IP address and may also
        advertise it to clients through its OpenID Connect Discovery
        endpoint.
@@ -120,7 +120,7 @@
    <section xml:id="module-services-keycloak-tls">
      <title>Setting up TLS/SSL</title>
      <para>
-       By default, <productname>Keycloak</productname> won't accept
+       By default, Keycloak won't accept
        unsecured HTTP connections originating from outside its local
        network.
      </para>

nixos/modules/services/x11/desktop-managers/pantheon.xml

@@ -85,7 +85,7 @@ switchboard-with-plugs.override {
     </term>
     <listitem>
      <para>
-      Open Switchboard and go to: <guilabel>Administration</guilabel> → <guilabel>About</guilabel> → <guilabel>Restore Default Settings</guilabel> → <guibutton>Restore Settings</guibutton>. This will reset any dconf settings to their Pantheon defaults. Note this could reset certain GNOME specific preferences if that desktop was used prior.
+      Open Switchboard and go to: Administration → About → Restore Default Settings → Restore Settings. This will reset any dconf settings to their Pantheon defaults. Note this could reset certain GNOME specific preferences if that desktop was used prior.
      </para>
     </listitem>
    </varlistentry>