base: Add a link to documentation in the remote GDB header file.

Change-Id: I34bf4d24e58e6dfc8e8d1220a158c90fd0935e47
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/44608
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Boris Shingarov <shingarov@gmail.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/base/remote_gdb.hh

@@ -58,6 +58,13 @@
 #include "cpu/pc_event.hh"
 #include "sim/eventq.hh"
 
+/*
+ * This file implements a client for the GDB remote serial protocol as
+ * described in this official documentation:
+ *
+ * https://sourceware.org/gdb/current/onlinedocs/gdb/Remote-Protocol.html
+ */
+
 class System;
 class ThreadContext;