Improve documentation. MA players and Examples

[OzGav]

why are you using the music assistant service for this and not just the regular play_media service ? it has everything you need...

TBH, when asking this question, I wasn't fully aware of the fact, that the mass media player entities are acting like regular media players in Home Assistant. Maybe this is trivial knowledge for long time MA users, but some weeks ago I didn't even know about MA and for me as a first time user, the installation and usage instructions on the Github page weren't that clear about how to actually use MA. Maybe some config examples would have make this easier to understand, but as of now, it's hard to find any real world configs from other MA users.

Originally posted by @derandiunddasbo in https://github.com/music-assistant/hass-music-assistant/discussions/725#discussioncomment-3374340