Broken ROS 2 Documentation Links

[CursedRock17]

Around the docs for this package, there are various ROS 2 documentation links that are broken, mainly in part due to using index.ros.org opposed to docs.ros.org (where documentation is now hosted for each ROS package). A search around the repo shows various spots in which the docs are wrong, for instance:

https://index.ros.org/doc/ros2/Installation/Crystal/Linux-Install-Debians/

should instead be:

https://docs.ros.org/en/crystal/Installation/Linux-Install-Debians.html

I currently don't have the bandwidth to solve this, but it's a simple solution, perhaps great for new contributors.