Mention bot config (#1384)
Mention bot config (#1384)

* Add mention bot config.

- Don’t mention BurtBiel
- And allow mention bot to auto assign to what it thinks is the best reviewer.

* Always notify for docs/help

yugangw-msft/azure-cli,yugangw-msft/azure-cli,QingChenmsft/azure-cli,QingChenmsft/azure-cli,samedder/azure-cli,yugangw-msft/azure-cli,yugangw-msft/azure-cli,samedder/azure-cli,QingChenmsft/azure-cli,samedder/azure-cli,yugangw-msft/azure-cli,samedder/azure-cli,yugangw-msft/azure-cli,QingChenmsft/azure-cli