SEP 31: Replace freenode references with liberachat.

[MTecknology]

Freenode staff have now rolled out two waves of hostile channel
takeovers on the Freenode network. The #salt channel that served as
SaltStack'ss/SaltProject's primary IRC channel for many years is one
such channel that was taken over.

We have largely already migrated to the new LiberaChat network.

See saltstack/salt#60261

[welcome]

Hello! Thank you for submitting a Salt Enhancement Proposal! Our process is detailed in the README.md and more about the SEP Life-cycle. An Open Core Team member will be assigned to follow up and help guide this SEP soon and you will find the this in the Community Slack channel #sep.
Please be sure to review our Code of Conduct.
You can also check out some of our community
resources:
- Community Wiki
- Salt’s Contributor Guide
- Join our Community Slack
- IRC on Freenode
- SaltStack YouTube channel
- SaltStackInc Twitch channel

[sagetherage]

once approved I will also update saltproject.io where link to IRC on the home page

[sagetherage]

@MTecknology want to also update the readme, here? my mistake I missed the link to the PR with the readme changes - apologies!

[MTecknology]

So, ehm... what's it going to take to finally get this approved? The freenode side of this no longer exists and we've all move over to libera (including the matrix link to slack).

[welcome]

Congratulations on your first PR being merged! 🎉