Do not add onos prefix when specifying branch in TestON master trigger job

Change-Id: If78ef5325037c6e9eb7284b50b2aacd3e3bd65e2
diff --git a/jjb/OnosSystemTest/onos-test-pipeline.yaml b/jjb/OnosSystemTest/onos-test-pipeline.yaml
index f56a085..c47a8d9 100644
--- a/jjb/OnosSystemTest/onos-test-pipeline.yaml
+++ b/jjb/OnosSystemTest/onos-test-pipeline.yaml
@@ -107,7 +107,7 @@
       - text:
          name: branches
          default: ""
-         description: "ONOS and TestON version to run on."
+         description: "ONOS and TestON version to run on. E.g. 1.15"
 
       - text:
          name: Tests