create a trigger option when pull requests are created

[saimsh]

hi team, 

i am currently developing a wiki framework in azure devops for azure css and azure linux ninjas to consume. 

As i attempt to automate the flow where a set of reviewers get notified in teams channel when a pull request is submitted to the master, i could not find option to trigger a notification when pull requests gets created. there is only an option for notification when a push is performed. 

[jemartin]

This would add a lot of value to my team.