Porting Bloom documentation to ROS2

[ijnek]

Releasing-a-ROS-2-package-with-bloom points to the ROS1 tutorials, but this is getting harder to follow due to:

• Difference in release procedure between ROS1 and ROS2 (like ros2-gbp)
• Many people striaght-up learn ROS2 now, following a ROS1 tutorial and adapting to ROS2 is hard

It makes sense to port documentation on wiki.ros.org across and adapt them for ROS2. If this has not been done yet because it's time-consuming I can get things started with #2357. Hopefully myself or others can get to other parts of the list below before I do.

Here is a list of existing tutorials that will (maybe) be ported:

• Releasing a package for the first time - Porting across bloom documentation #2375
• Releasing a new version of a catkin package - Porting across bloom documentation #2375
• Releasing a third party package
• Releasing for a new ROS distro
• Running a pre-release test
• Changing the default build flags for a package
• Manually authorizing bloom to create rosdistro PRs on github - Porting across bloom documentation #2375
• Register a GitHub repository for pull request testing

[clalancette]

Yes please! In general we want to get away from referencing the ROS 1 wiki, so if you have time to port that over we would be happy to review.