Update file-attachments-on-issues-and-pull-requests.md

[daminebenq]

Why:

Now Github supports mp4 file attachments. So i saw that it is missing in this list.

What's being changed:

file-1.mp4

Check off the following:

• I have reviewed my changes in staging. (look for the deploy-to-heroku link in your pull request, then click View deployment)
• For content changes, I have reviewed the localization checklist
• For content changes, I have reviewed the Content style guide for GitHub Docs.

[welcome]

Thanks for opening this pull request! A GitHub docs team member should be by to give feedback soon. In the meantime, please check out the contributing guidelines.

[janiceilene]

@daminebenq Thanks so much for opening a PR! I'll get this triaged for review ⚡

[felicitymay]

👋🏻 Hi @daminebenq - thanks for taking the time to open this PR.

You're right to say that GitHub now supports mp4 attachments. It was announced as a beta feature: https://github.blog/changelog/2020-12-16-video-upload-public-beta/ and https://github.blog/changelog/2021-02-01-expanded-support-for-video-uploads/.

It looks as if someone else has also opened a PR to update to this page. Since that PR also adds the limit on file sizes, I'm closing your PR in favor of: #3571.