Add new entries under 'Recent News': 'Urgent' and 'Community' and remove 'Announcements'

The Urgent tag is meant to show prioritary communications that the community should be aware of as soon as possible 'Community' will show all non-urgent communications and general blog posts.

zh-tw, zh-cn, tr, ru, pt-br, pl, nl, ar and partly fr are untranslated. I will ask to the Monero Localization Workgroup and the community to help with the translations. We only need to translate two words: Community and Urgent.

I suggest to review each commit singularly.

Closes #1025 (closed)