cmd: document Rosa OS programs

The earlyinit and mbf program are not covered by the compatibility promise, so specify that here.

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/mbf/main.go

@@ -1,3 +1,15 @@
+// The mbf program is a frontend for [hakurei.app/internal/rosa].
+//
+// This program is not covered by the compatibility promise. The command line
+// interface, available packages and their behaviour, and even the on-disk
+// format, may change at any time.
+//
+// # Name
+//
+// The name mbf stands for maiden's best friend, as a tribute to the DOOM source
+// port of [the same name]. This name is a placeholder and is subject to change.
+//
+// [the same name]: https://www.doomwiki.org/wiki/MBF
 package main
 
 import (