[PATCH 05 of 10 RFC v2] help: document compat mode

[David Soria Parra]

# HG changeset patch
# User David Soria Parra <davidsp at fb.com>
# Date 1489349206 25200
#      Sun Mar 12 13:06:46 2017 -0700
# Node ID d402acdf7c439dc369b6ab3a6888078a2895978a
# Parent  0986fb7be0f584f5169f93377f9d013f87381ea7
help: document compat mode

diff --git a/mercurial/help/config.txt b/mercurial/help/config.txt
--- a/mercurial/help/config.txt
+++ b/mercurial/help/config.txt
@@ -1837,6 +1837,13 @@
     changes, abort the commit.
     (default: False)
 
+``compat``
+    String: Compatibility mode for the ui. Possible values are compat
+    or latest (default: compat). ``compat`` provides backwards compatible
+    ui behavior. ``latest`` enables additional config settings aiming to
+    improve user experience. (see ``HGPLAIN`` for compatibility modes in
+    non-interactive environments)
+
 ``debug``
     Print debugging information. (default: False)