ROS Humble branch request

[dfarning]

Could you please create a humble branch and build it so we can test and update documentation prior to the official humble release later this month?

[chapulina]

Thanks for the ticket! I'd like to avoid branching off for Humble if possible, it's better to maintain less branches.

I started https://github.com/chapulina/dolly/pull/49 to enable CI for Humble out of the galactic branch.