doc: add command docs page, canonicalize reference paths

R=golang-dev, kyle, r
CC=golang-dev
https://golang.org/cl/5728055
diff --git a/doc/debugging_with_gdb.html b/doc/debugging_with_gdb.html
index d5c1a88..43977b7 100644
--- a/doc/debugging_with_gdb.html
+++ b/doc/debugging_with_gdb.html
@@ -1,5 +1,6 @@
 <!--{
-	"Title": "Debugging Go Code with GDB"
+	"Title": "Debugging Go Code with GDB",
+	"Path": "/ref/gdb"
 }-->
 
 <p><i>