Update documentation to clone from beijing branch

Change-Id: I93a5f7628ba030a2250e6f0c62458dbd5398cbe9
Signed-off-by: Roger Maitland <Roger.Maitland@amdocs.com>
Issue-ID: OOM-1129
diff --git a/docs/oom_user_guide.rst b/docs/oom_user_guide.rst
index e63120f..f79de59 100644
--- a/docs/oom_user_guide.rst
+++ b/docs/oom_user_guide.rst
@@ -108,7 +108,7 @@
 
 To prepare your system for an installation of ONAP, you'll need to::
 
-  > git clone http://gerrit.onap.org/r/oom
+  > git clone -b beijing http://gerrit.onap.org/r/oom
   > cd oom/kubernetes