add a tutorial

README.md

@@ -27,6 +27,18 @@ Source code: https://codeberg.org/outfly/outfly
 - Written in [Rust](https://www.rust-lang.org) with the [Bevy game engine](https://bevyengine.org)
 - Status: Early access, not much content
 
+# Tutorial
+
+OutFly has typical game controls like mouse movement, `A/W/S/D` for horizontal movement, `Ctrl/Shift` for vertical movement.  But in space, there is no friction to slow you down after the movement. [You just keep on moving](https://en.wikipedia.org/wiki/Newton%27s_laws_of_motion#First_law), until you hit something or accelerate in the opposite direction.
+
+The `SPACE` key helps you move more intuitively by slowing you down.  Hold it for a while to come to a halt.  Combine it with movement keys for slower, more precise movement.  You can also click to select another object and then hold the `SPACE` key to **match your velocity** to the target object.  Essential for spaceflight!
+
+When you're ready, take a look around, explore the starting area. There is a friendly person floating nearby in a red space suit that would love to talk to you.
+
+Press the `ESC` key for the menu to restart the game if you get lost, explore more key bindings, game features, and the **achievements** to get some guidance on what you can do in the game.
+
+But in the end, OutFly is an open world game with no true goals other than the ones you set for yourself.  Just lean back, get cozy, and drift towards whatever catches your eye :)
+
 # Controls
 
 Press **ESC** to view these any time from the in-game menu.