docs(ws-tutorial): add a WebSocket tutorial

[derkweijers]

Summary of Changes

Add a tutorial on how to work with websockets in a Falcon app. This is to be read as a quickstart, linking to the reference page for more info.

Related Issues

Closes #2240

Pull Request Checklist

This is just a reminder about the most common mistakes. Please make sure that you tick all appropriate boxes. But please read our contribution guide at least once; it will save you a few review cycles!

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• [x] Applied changes to both WSGI and ASGI code paths and interfaces (where applicable).
• [x] Added tests for changed code.
• [x] Prefixed code comments with GitHub nick and an appropriate prefix.
• [x] Coding style is consistent with the rest of the framework.
• [x] Updated documentation for changed code.
  • [x] Added docstrings for any new classes, functions, or modules.
  • [x] Updated docstrings for any modifications to existing code.
  • [x] Updated both WSGI and ASGI docs (where applicable).
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PR template inspired by the attrs project.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 36.17%. Comparing base (89b5fb0) to head (4dcb8a6).

:exclamation: There is a different number of reports uploaded between BASE (89b5fb0) and HEAD (4dcb8a6). Click for more details.

HEAD has 1 upload less than BASE

| Flag | BASE (89b5fb0) | HEAD (4dcb8a6) | |------|------|------| ||2|1|

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2245 +/- ## ============================================ - Coverage 100.00% 36.17% -63.83% ============================================ Files 63 63 Lines 6852 6852 Branches 1260 1260 ============================================ - Hits 6852 2479 -4373 - Misses 0 4315 +4315 - Partials 0 58 +58 ```

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[derkweijers]

Ah, it seems we forgot to commit wslook/.coveragerc. Do you maybe have the file lying anywhere around @derkweijers?

Yes! Added it to the repo.

[CaselIT]

I guess I've arrived too late with the review, @vytas7 you mentioned you wanted to cleanup something else, maybe you can incorporate the suggestions?

@derkweijers thanks for the great tutorial, and for participating in the sprint!

[vytas7]

@CaselIT yeah, thanks! Just add these suggestions to #2255