docs: show a coroutine-based implementation of the echo server in the tutorial

[Dobiasd]

Hi,

this pull request is meant mainly as a proposal. For me, it was eye-opening to convert the continuation-based implementation of the TCP-echo server to coroutines. So I thought seeing this might help others too. But I don't know if it makes sense to have it in the tutorial. So, if you don't see fit, I'd fully understand if you simply close this PR without merging. :relaxed:

[avikivity]

/cc @nyh

[Dobiasd]

If you have any suggestions on what I can do to help move this PR forward, please let me know. In case it's currently not wanted, and you'd prefer to close this unmerged, that's also ok for me. :relaxed:

[avikivity]

If you have any suggestions on what I can do to help move this PR forward, please let me know. In case it's currently not wanted, and you'd prefer to close this unmerged, that's also ok for me. ☺️

Replace the continuations based example with the coroutine. There's no reason to show both.

[Dobiasd]

Thanks! I just did that in this commit which also adjusts the explanation text accordingly. :heavy_check_mark:

[Dobiasd]

If there is any way I can help move this forward, please let me know.