GitHub app on the mobile phone always displsays <!-- YOU HAVE TO ... as preview text. I think, I cannot convince GitHub to update their app to "correctly" render the PR text.

I think, adding "PLEASE DELETE THIS TEXT" is not a good instruction.

Thus, I propose to re-order the text in the PR template.

Mandatory checks

• I own the copyright of the code submitted and I license it under the MIT license
• [.] Change in CHANGELOG.md described in a way that is understandable for the average user (if change is visible to the user)
• [.] Tests created for changes (if applicable)
• [.] Manually tested changed features in running JabRef (always required)
• [.] Screenshots added in PR description (if change is visible to the user)
• [.] 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.