status: add relative directory help text (issue3835)

Previously, it was difficult to find out how to display the status of files
relative to your current working directory. This patch adds that knowledge to
the help text.

mercurial/commands.py

@@ -5736,6 +5736,11 b' def status(ui, repo, *pats, **opts):'
 
           hg status --rev 9353
 
+      - show changes in the working directory relative to the
+        current directory (see :hg:`help patterns` for more information)::
+
+          hg status re:
+
       - show all changes including copies in an existing changeset::
 
           hg status --copies --change 9353