irc meetings: remove p2p meeting

[fanquake]

This meeting is not regularly happening, and the last one was quite some time ago, remove its mention for now.

[harding]

There's a page for the general meeting on the devwiki. I suggest that we just update this page to link to there so that future changes to the meetings and schedules doesn't need to go through this site's review process.

https://github.com/bitcoin-core/bitcoin-devwiki/wiki/General-IRC-meeting

[fanquake]

I suggest that we just update this page to link to there so that future changes to the meetings and schedules

I assume you meant link to both, as the general meeting and wallet meeting have different pages on the wiki. Have done that now.