Document best practice on setting QoS settings for topics

[azeey]

As mentioned in #581, for example, the clock topic should use the ClockQoS setting. It would be nice if we had a list of recommended QoS settings for different types of topics.

[Kametor]

Hi, I encountered a similar issue when using ros_gz_bridge with a high-bandwidth camera topic and a pose topic. When both are bridged together in the same instance, I experienced significant lag in pose updates.

Following the recommendation in Issue #581, running the camera topic in a separate ros_gz_bridge instance solved the problem. This workaround took me hours to figure out, so it might be worth addressing this with a better fix, like default QoS settings or improved multithreading support 😊