Update README.md to include contributing and building references.

Change-Id: I174ee86c2c25228a0fa47748efddbf2725cc5a8b
Signed-off-by: Frank S. Filz <[email protected]>

Author: ffilz

README.md

@@ -5,3 +5,13 @@ nfs-ganesha
 NFS-Ganesha is an NFSv3,v4,v4.1 fileserver that runs in user mode on most UNIX/Linux systems.  It also supports the 9p.2000L protocol.
 
 For more information, consult the [project wiki](https://github.com/nfs-ganesha/nfs-ganesha/wiki).
+
+# CONTRIBUTING
+
+Code contributions to Ganesha are managed by submission to gerrithub for review. We do not merge from github pull requests.
+
+See src/CONTRIBUTING_HOWTO.txt for details.
+
+# BUILDING
+
+See src/COMPILING_HOWTO.txt