Update CONTRIBUTING.md CLA signer reference

Change-Id: I16e2c75295d14a943d92d2c1f5096e11c5c66f8b
Signed-off-by: George Keishing <gkeishin@in.ibm.com>
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index eb8f42f..c57512c 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -5,6 +5,7 @@
 
 Submitting changes via Gerrit server
 ------------------------------------
+-   Reference [OpenBMC CLA signers](https://github.com/openbmc/openbmc-tools/blob/master/emilyshaffer/cla-signers/cla-signers)
 -   Reference [OpenBMC docs](https://github.com/openbmc/docs/blob/master/contributing.md#submitting-changes-via-gerrit-server)
 
 Robot Coding Guidelines