plan9: finalize documentation for next release

contrib/plan9/hgrc.d/9diff.rc

@@ -1,3 +1,5 @@
+# The 9diff extdiff command generates diff(1) compatible output
+# suitable for use with the plumber(4).
 [extensions]
 extdiff =
 

contrib/plan9/hgrc.d/factotum.rc

@@ -1,2 +1,4 @@
+# The factotum extension permits factotum(4) to act as an
+# authentication agent for HTTP repositories.
 [extensions]
 factotum =

contrib/plan9/proto

@@ -17,4 +17,7 @@ sys	- sys sys
 							+	- sys sys
 						mercurial	- sys sys
 							+	- sys sys
-						mercurial-2.1.1-py2.5.egg-info	- sys sys
+						mercurial-VERSION-py2.5.egg-info	- sys sys
+	src	- sys sys
+		cmd	- sys sys
+			mercurial	- sys sys