Polish Feature page

[jholdstock]

The current features page is too technical and too verbose.

Things like double ratcheting, PQ-PKI infrastructure and PostgreSQL are boring implementation details. Great to have that stuff documented for advanced users, but it's content for a blog post or documentation site.

https://bisonrelay.org/ will be the main entrypoint for normies so needs to be chad-ified.

Features normies actually care about: DMs, group chats, LN tipping, file sharing, no censorship, anti-spam measures