Add Nextcloud to cloud & foss-app sections

Content request

✏ Suggest ideas for new content!

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 content request, and not a bug report, feature request, or anything other

What are you missing or what could be improved?

About the self-hosted cloud service ...why not nextcloud?

Do you have additional comments?

N/A