help: format ``commands`` heading correctly
The number of dashes under it needs to match exactly for it to be
rendered as a heading. Without this change, the dashes end up on the
same line as "commands", and "hg help config.commands" does not work.
--- a/mercurial/help/config.txt Wed Mar 22 14:12:58 2017 -0500
+++ b/mercurial/help/config.txt Wed Mar 22 16:36:53 2017 -0700
@@ -415,7 +415,7 @@
extension).
``commands``
-----------
+------------
``status.relative``
Make paths in ``hg status`` output relative to the current directory.