Fix directions for running unit tests.
Fix directions for running unit tests.

Add discussion for usage of -q.
yugangw-msft/azure-cli,BurtBiel/azure-cli,samedder/azure-cli,samedder/azure-cli,yugangw-msft/azure-cli,yugangw-msft/azure-cli,samedder/azure-cli,QingChenmsft/azure-cli,yugangw-msft/azure-cli,QingChenmsft/azure-cli,samedder/azure-cli,QingChenmsft/azure-cli,BurtBiel/azure-cli,QingChenmsft/azure-cli,yugangw-msft/azure-cli,yugangw-msft/azure-cli