I was wondering how a default PR template could be set for a GitHub organisation, but I found it a little difficult to find official documentation on the subject (though there is a support thread on the subject).

The secret is to:

  1. Create a repository within your organisation called .github (a special repository where other default files like a license or code of conduct can be collected).
  2. Create a PULL_REQUEST_TEMPLATE.md file there, either in the root directory, or within a directory called .github. This file is a markdown document which can be edited in the same way as a pull request.

This template can be overridden in a specific repository by adding a PULL_REQUEST_TEMPLATE.md there.

Some examples: