New Diffs: Definition of Done

GitLab has an existing definition of done which is geared primarily toward identifying when an MR is ready to be merged.

In addition to the items in GitLab's definition of done, work on New Diffs should also adhere to the following requirements:

1. Meets or exceeds our technical metrics
2. Meets or exceeds our minimum accessibility metrics
3. Updates/Creates technical documentation covering the changes for developers