[PATCH 2 of 2] doc: improves merge-tools example with a vimdiff one

[Pierre-Yves David]

# HG changeset patch
# User Pierre-Yves David <pierre-yves.david at logilab.fr>
# Date 1343908294 -7200
# Branch stable
# Node ID b0c46da50e50eb93ca61c865a38e711705172a0a
# Parent  3b955dc3df50e296e19b244f85464f68121fb292
doc: improves merge-tools example with a vimdiff one

The vimdiff example show the `check` argument and explicit way `priority` works.
Another benefit is to have the vimdiff configuration directly available in the
doc. This is valuable as vimdiff is a common request from user.

diff --git a/mercurial/help/config.txt b/mercurial/help/config.txt
--- a/mercurial/help/config.txt
+++ b/mercurial/help/config.txt
@@ -809,6 +809,13 @@
   myHtmlTool.regkey = Software\FooSoftware\HtmlMerge
   myHtmlTool.priority = 1
 
+  # Define fallback tool
+  vimdiff.args=$local $other $base
+  # detect unchanged files as potential conflict
+  vimdiff.check=changed
+  # give priority lower than gui tool
+  vimdiff.priority=0
+
 Supported arguments:
 
 ``priority``