Encourage and ensure that we make documentation changes with feature MRs

From PM/Eng meeting agenda https://docs.google.com/document/d/1D9rW65d4w0UwSRw_0jJMRk5wAxdhAd4ynrHLbMMwIjo/edit?ts=5f7623b7#bookmark=id.46lqwm2m6w4r

• Sid: Bot message that ensure we change /docs with new features.

  • Eric: On feature::enhancement.

  • Christie: I was about to mention.

Plan

• Decide if we want this on featureaddition and also featureenhancement
• Dangerbot mechanism to ensure that we ship documentation along with these work streams
• Consider blocking on merge

Challenge

• featureenhancement has not completed yet
• Consider how to positively encourage engineers so we don't get bypass behaviours

@clefelhocz1 @clenneville @adawar

Creating the issue here due to it likely being danger vs triage-ops.