Group webhooks REST API is not documented nor implemented

• Documents Group Hooks
• Follow-up from: #XXX, !YYY

New doc or update?

• New documentation
• Update existing documentation

Checklists

Product Manager

• Add the correct labels
• Add the correct milestone
• Indicate the correct document/directory for this feature
• Fill the doc blurb below

Documentation blurb

• Doc Groups API

• Feature Hooks

• List group hooks
• Get group hook
• Add group hook
• Edit group hook
• Delete group hook

Developer

• Copy the doc blurb above and paste it into the doc
• Write the tutorial - explain how to use the feature
• Submit the MR using the appropriate MR description template