Add Issue & Merge Request templates

Feature request

🚀 Suggest ideas for new website features!

Checklist

• This issue is not a duplicate, I've searched the Issue Tracker
• This issue is not a question, I'm aware that I can submit questions via Mastodon, Twitter, Email, Reddit or Matrix
• This issue is a feature request, and not a bug report, content request, or anything other

What are you missing or what could be improved?

Add issue templates:

1. content request
2. feature request
3. bug report

Add merge request template.

Do you have additional comments?

N/A