Move to Discord as the main chat system

[padovan]

Recently the TSC approved moving our main chat system to Discord. Additionally there will be a Matrix bridge maintained by @aliceinwire

• Update community page with the Discord info https://kernelci.org/community-contact/
• List Discord in the in the Community menu at https://kernelci.org
• Docs: Update chat to Discord and list new admins
• Finish matrix setup and document it
• Announce the transition to Discord in the mailing list
• Docs: add a contact page with chat(Discord, IRC and Matrix bridge) and mailing list details
• Setup IRC bridge and document it

[padovan]

@aliceinwire is the matrix setup documented in kernelci docs?