[PATCH 1 of 2] help: clarify that the config hook priority prefix includes a period

[timeless]

# HG changeset patch
# User timeless <timeless at mozdev.org>
# Date 1451401204 0
#      Tue Dec 29 15:00:04 2015 +0000
# Node ID 9d03acd2fe2e350d1fb3449a4f2543be4a025c08
# Parent  23541bdd1610c08af247f9c8719045cf247ce541
help: clarify that the config hook priority prefix includes a period

diff --git a/mercurial/help/config.txt b/mercurial/help/config.txt
--- a/mercurial/help/config.txt
+++ b/mercurial/help/config.txt
@@ -734,7 +734,7 @@
 hooks can be run for the same action by appending a suffix to the
 action. Overriding a site-wide hook can be done by changing its
 value or setting it to an empty string.  Hooks can be prioritized
-by adding a prefix of ``priority`` to the hook name on a new line
+by adding a prefix of ``priority.`` to the hook name on a new line
 and setting the priority. The default priority is 0.
 
 Example ``.hg/hgrc``::