Add rosbag2 qos override documentation

[piraka9011]

rosbag2 added a new feature for Foxy where users can specify QoS policy overrides from the CLI to record/playback topics offering different QoS policies.

This adds documentation on how to use the feature.

Part of ros2/rosbag2#125 and ros2/rosbag2#357.
Part of ros-tooling/aws-roadmap#244.

Signed-off-by: Anas Abou Allaban [email protected]

[piraka9011]

@maryaB-osr Could I get a review on this please?
Let me know whether I need to move things around.

[maryaB-osr]

It looks like your Tutorials.rst page is out of date. The sections are organized a bit differently now: https://index.ros.org/doc/ros2/Tutorials/

So there is actually an intermediate section you can put this tutorial in

[maryaB-osr]

It looks like there's no merge conflict even though Tutorials.rst is out of date. So I'll approve it anyway, this tutorial can be moved to the right section any time. You probably want to update your fork though.

Thanks for the content!