[PATCH 1 of 8 V2] mdiff.diffopts: add doc comment for nobinary

[Siddharth Agarwal]

# HG changeset patch
# User Siddharth Agarwal <sid0 at fb.com>
# Date 1415863184 28800
#      Wed Nov 12 23:19:44 2014 -0800
# Node ID a4a3123dcdedda92ae4be68e1521da4bebcc17ca
# Parent  125c7bc0d2dcb013685a32ed8ee406ad5aa5f7b5
mdiff.diffopts: add doc comment for nobinary

diff --git a/mercurial/mdiff.py b/mercurial/mdiff.py
--- a/mercurial/mdiff.py
+++ b/mercurial/mdiff.py
@@ -25,6 +25,7 @@
     showfunc enables diff -p output
     git enables the git extended patch format
     nodates removes dates from diff headers
+    nobinary ignores binary files
     ignorews ignores all whitespace changes in the diff
     ignorewsamount ignores changes in the amount of whitespace
     ignoreblanklines ignores changes whose lines are all blank