Remove source_ref: master from demo docs

labs/consultant/03-Exporters.md

@@ -46,7 +46,6 @@ In the next few sections, we'll deploy some exporters that collect data in a sim
         extraEnv:
         - name: APP_FILE
           value: deploytime/app.py
-        source_ref: master
         source_url: https://github.com/redhat-cop/pelorus.git
 
 We get the information we need about deploy time from OpenShift, so this exporter works out-of-the-box!
@@ -74,7 +73,6 @@ Update the `values.yaml` and then upgrade our helm installation of Pelorus to ad
         extraEnv:
         - name: APP_FILE
           value: committime/app.py
-        source_ref: master
         source_url: https://github.com/redhat-cop/pelorus.git
 
       helm upgrade pelorus charts/pelorus --namespace pelorus
@@ -114,7 +112,6 @@ Once again, we will update our values.yaml and upgrade our Pelorus deployment.
         extraEnv:
         - name: APP_FILE
           value: failure/app.py
-        source_ref: master
         source_url: https://github.com/redhat-cop/pelorus.git
 
       helm upgrade pelorus charts/pelorus --namespace pelorus