Add predefined CI variable for merge request description
I want to be able to read and work with the merge request description in a merge request pipeline.
Having the variable $CI_MERGE_REQUEST_DESCRIPTION
(like $CI_COMMIT_DESCRIPTION
) would solve this.
Documentation blurb
To add in https://docs.gitlab.com/ce/ci/variables/README.html#predefined-variables-environment-variables
CI_MERGE_REQUEST_DESCRIPTION The description of the merge request, if any.