[PATCH 1 of 3] merge: add some useful documentation

[Ryan McElroy]

# HG changeset patch
# User Ryan McElroy <rmcelroy at fb.com>
# Date 1455060309 28800
#      Tue Feb 09 15:25:09 2016 -0800
# Node ID d520165147534eabfd95d66df6f176809a4c5b03
# Parent  a036e1ae1fbe88ab99cb861ebfc2e4da7a3912ca
merge: add some useful documentation

diff --git a/mercurial/simplemerge.py b/mercurial/simplemerge.py
--- a/mercurial/simplemerge.py
+++ b/mercurial/simplemerge.py
@@ -195,6 +195,9 @@ class Merge3Text(object):
         'a', start, end
              Non-clashing insertion from a[start:end]
 
+        'conflict', zstart, zend, astart, aend, bstart, bend
+            Conflict between a and b, with z as common ancestor
+
         Method is as follows:
 
         The two sequences align only on regions which match the base