Include additional information in merge request email notification
<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=15352) </details> <!--IssueSummary end--> #### Overview A customer is trying to apply email filtering based on merge request email notifications. They're requesting to filter by the following attributes: * The target branch for the merge request * Something in the email that says it's a merge request Currently the [merge request note notification](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/app/views/notify/note_merge_request_email.html.haml) does not contain this information. #### Proposal Update the email note MR template to include the target branch and the words "Merge request" _____ ZD: https://gitlab.zendesk.com/agent/tickets/28115
issue