Sidecar repo created

[Jason Brown <ja...@gmail.com>]

Hello all,

In moving the sidecar project forward, I've created a gitbox [1] repo for
the cassandra-sidecar which is located at:

git: https://gitbox.apache.org/repos/asf/cassandra-sidecar.git
github: https://github.com/apache/cassandra-sidecar

There are additional behaviors we can set on the repo [2]:


   1. Any Pull Request that gets opened, closed, reopened or commented on
   can get recorded on the project's mailing list
   2. If a project has a JIRA instance, any PRs or comments on PRs that
   include a JIRA ticket ID will trigger an update on that specific ticket
   (unless opted out of)
   3. GitHub activity can be relayed to IRC channels on the Freenode
   network.

I think we probably want to enable #1 & #2 to maintain parity with what we
have already with the main cassandra repo.

Thanks,

-Jason

[1] https://gitbox.apache.org/
[2] https://reference.apache.org/pmc/github