Update documentation around the requirement for merge_request_diff_head_sha when using /merge quick action
We have expanded the usage of merge_request_diff_head_sha to be used in the api and graphql.
This parameter is used to ensure that when a user is attempting to use the /merge quick action, they have to pass in a merge_request_diff_head_sha, to ensure that the sha they are looking at, is the most up to date version.
The merge_request_diff_head_sha parameter should be the sha of the head diff.
The relevant lines changed in regard to errors returned to the user:
Relevant quick action docs:
Note: For the quick action in the UI it is automatically passed in. It is only needed for the API/GraphQL.
Edited by Marc Shaw