Update local testing README to include cli version (#198)

Author: samiyaakhtar

tests/README.md

@@ -148,7 +148,10 @@ When testing locally you don't need to do the above set up since there is no
 pipeline. Instead run these steps:
 
 1. Login into AZ CLI
-2. Install Azure DevOps Extension
+2. Install Azure DevOps Extension (make sure you have version >= 0.17.0 installed) 
+   ```
+   az extension add --name azure-devops
+   ```
 3. Set the following environment variables
    <pre>
    export SPK_LOCATION=<b>REPLACE_ME</b>