Missing documentation for websocket communication

[lesquoyb]

Is your request related to a problem? Please describe.
I noticed that there are now some operators available to interact with clients when gama is running in server mode, but apart from the operators documentation (which is very minimalist) I think there's no explanation of how it works and what are the possibilities.
I think a small tutorial/recipe to showcase the few operators/lifecycle of the interaction and how it could be interesting to use would be nice.
Also I noticed that those operators do not take into consideration that there may be multiple clients. I guess it is because they were developed with a special use case in mind and rework those operators to be generic is out of the scope of this issue, but it should be told to the user explicitly that they only are interacting with the latest client.

So far I've seen the send action (sendMessageThroughServer) and send_image_to_websocket (sendImageWebsocket), maybe there are others.

Btw we should also probably rename the send action as it's conflicting with the send action in the network skill (unless merge both in the network skill, which would also make sense)