Add "After submission of a pull request"

[koppor]

Some contributors want to re-create a pull request (e.g., #12009 (comment)).

Therefore, I added some text to CONTRIBUTING.md.

Mandatory checks

• I own the copyright of the code submitted and I licence it under the MIT license
• Change in CHANGELOG.md described in a way that is understandable for the average user (if applicable)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked developer's documentation: Is the information available and up to date? If not, I outlined it in this pull request.
• Checked documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request to the documentation repository.

[github-actions]

You modified Markdown (*.md) files and did not meet JabRef's rules for consistently formatted Markdown files.
To ensure consistent styling, we have markdown-lint in place.
Markdown lint's rules help to keep our Markdown files consistent within this repository and consistent with the Markdown files outside here.

You can check the detailed error output by navigating to your pull request, selecting the tab "Checks", section "Tests" (on the left), subsection "Markdown".

[github-actions]

The build of this PR is available at https://builds.jabref.org/pull/12010/merge.

[github-actions]

The build of this PR is available at https://builds.jabref.org/pull/12010/merge.

[github-actions]

The build for this PR is no longer available. Please visit https://builds.jabref.org/main/ for the latest build.