[Proposal] DNS name for Tour of Beam site

[Kerry Donny-Clark via dev <de...@beam.apache.org>]

Hi all,
I would like to update everyone on a small DNS change for the Tour Of Beam,
a new Beam interactive learning app we've been working on. We are excited
to get it live and share it with the community, and one of the remaining
steps for us is to make a DNS record for 'tour.beam.apache.org' and point
it to our production environment hosted in Firebase. This does not require
any action from you, but rather it's an update to the community about a
change to our infra. Feel free to ask questions if there are any, and look
out for a live Tour of Beam site as soon as we get this completed.

Kerry