[4.1] dd0e126 Clarify Github PR procedure.

[Lasse Karstensen]

commit dd0e126a9b3a44c63a5f972aa3f423d61a11407d
Author: Lasse Karstensen <lkarsten at varnish-software.com>
Date:   Fri Sep 4 11:37:36 2015 +0200

    Clarify Github PR procedure.

diff --git a/CONTRIBUTING b/CONTRIBUTING
index 3f15742..d7c0277 100644
--- a/CONTRIBUTING
+++ b/CONTRIBUTING
@@ -13,5 +13,11 @@ Official development tree is here:
 
 Patches can be sent to varnish-dev at varnish-cache.org.
 
-Documentation fixes and other small items for the documentation team may be
-sent as Github pull requests.
+
+Github pull requests
+--------------------
+
+Documentation updates and other non-trivial items for the documentation
+team may be sent as Github pull requests.
+
+Pull requests outside of this scope will be closed without review.