Update the documentation for releases

[directcuteo]

Add following channels of Discord as mandatory to leave the update there:

• #rust-node-testing
• #mina-web-node
• #mina-web-node-testing
• #rust-node-questions-and-feedback

https://github.com/o1-labs/mina-rust/blob/develop/website/docs/appendix/release-process.mdx#release-communication-checklist

• update the Slack channel to #releases instead of #announcements

• Platform lead contacted for infrastructure updates should be rephrased into Platform lead contacted for infrastructure updates and a PR on gitops-infrastructure has been opened and merged to update to the latest release