Symfony Slack channels cleanup and rules reminder

The Symfony community gathers together for community support, discussions and daily chitchatting on Slack.

We want the Symfony Community and conversations on Slack to be friendly and welcoming to everyone. But lately, the randomness of the #random Slack channel has shown some cases where the things said or discussed turned less friendly than we intended the channel to be. To ensure that the Symfony Slack stays as welcome as possible to all people, we have renamed the #random channel to #friendly-chitchat to signal that there are limits in what we can post on any Symfony Slack channel.

More generally, we'd like to remind everyone that the Code of Conduct is in effect in all Symfony Slack channels. From this point forward, we’ll be more strict towards people using language that is harmful to (groups of) people. This is a process and bear with us as we find a balance to keep all channels open and pleasant for everyone.

As the CARE team is quite small, we need to ease the moderation work. As a first step, we are going to reduce the number of public channels by removing all channels with no activity during the last year. If you've created a channel that is not needed anymore, we would appreciate your help by deleting it yourself. We've also restricted the creation of new channels to admins.