kernelPatches: Add pointer to ml threads for riscv patches.

pkgs/os-specific/linux/kernel/patches.nix

@@ -78,21 +78,25 @@ rec {
     patch = ./riscv-modules.patch;
   };
 
+  # http://lists.infradead.org/pipermail/linux-riscv/2018-February/000054.html
   riscv_irq_busy = {
     name = "riscv-irq-busy";
     patch = ./riscv-irq-busy.patch;
   };
 
+  # http://lists.infradead.org/pipermail/linux-riscv/2018-February/000059.html
   riscv_install = {
     name = "riscv-install";
     patch = ./riscv-install.patch;
   };
 
+  # http://lists.infradead.org/pipermail/linux-riscv/2018-February/000056.html
   riscv_initrd = {
     name = "riscv-initrd";
     patch = ./riscv-initrd.patch;
   };
 
+  # http://lists.infradead.org/pipermail/linux-riscv/2018-February/000058.html
   riscv_initrd_free = {
     name = "riscv-initrd-free";
     patch = ./riscv-initrd-free.patch;