Update community screen chat section

[soupslurpr]

Removed Telegram chat room link card and updated chat section description.

[mio-19]

Is telegram room not official anymore?

[thestinger]

Can you update this to the current wording on the site?

                <p>GrapheneOS has official chat rooms on Discord and Matrix. Discord provides a
                much better user interface and moderation tools so it's a better experience and
                far more active than Matrix. Matrix is an open platform with federation between
                servers. Our public chat rooms don't benefit from Matrix supporting end-to-end
                encryption but it's useful for private chats created between users in our rooms.
                We no longer bridge our chat rooms across platforms and don't plan on adding it
                back so Discord and Matrix have entirely separate chat rooms.</p>

[thestinger]

Maybe we could simplify it a bit by removing "and don't plan on adding it back" but I think it should be consistent.

[soupslurpr]

Current wording on the site seems good, it'll be bit longer but I think that's fine for the extra clarity and information along with consistency.

[soupslurpr]

Rebased and updated to current wording on the site.