Add announcements to Categories

[emmapeel2]

Describe the problem

We can add announcements on components, projects, and soon project languages.

We would like to have announcements on a project category as well.

Describe the solution you would like

Announcements on categories are useful to communicate information to translators.

See discussion in #10939

Describe alternatives you have considered

No response

Screenshots

No response

Additional context

No response

[github-actions]

This issue seems to be a good fit for newbie contributors. You are welcome to contribute to Weblate! Don't hesitate to ask any questions you would have while implementing this.

You can learn about how to get started in our contributors documentation.

[danqixu]

@emmapeel2 Hi, could you assign this issue to me? I am a student and having OSS course, would like to give a try.

[nijel]

@danqixu You can start working on the issue right now, we don't assign issues to outside collaborators.

[nijel]

@harriebird This is similar to #11003 which you've recently addressed.

[harriebird]

Hi @nijel, I will check this issue.

[harriebird]

Hi guys, check my PR #11644 for this issue.