docs: add mqtt 5 beta banner and sponsors section

[robertsLando]

Also did a quick lint fix on readme

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (4869f1e) 86.22% compared to head (0b5e78d) 86.22%.

❗ Current head 0b5e78d differs from pull request most recent head ca76bf9. Consider uploading reports for the commit ca76bf9 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1617   +/-   ##
=======================================
  Coverage   86.22%   86.22%           
=======================================
  Files          13       13           
  Lines        1314     1314           
=======================================
  Hits         1133     1133           
  Misses        181      181           

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[robertsLando]

cc @mcollina just to inform you, a sponsor section has been added to project README

[robertsLando]

Tests are flaky, hopefully #1534 will fix this

[robertsLando]

@vishnureddy17 FYI I tried to make a new beta release using the workflow. It went well except for the last step where it should push the release and changelog to main branch: https://github.com/mqttjs/MQTT.js/actions/runs/5409237552/jobs/9829130699#step:7:1054

I will see if/how I can fix this

[robertsLando]

OK seems the only way would be to use a personal access token sectet. In this way we can skip the branch protection checks. The secrets.GITHUB_TOKEN that is actually used in the workflow is a temporary token created for that workflow run and has not the right access for pushing the release commit/tag to main branch.

In order to do this you should go to mqttjs org and add a personal access token (let's name it GH_TOKEN) and then I can use it here. I would use a fine grained token so it has access only to this repo and has only the required permissions.

Let me know if you can do that. otherwise that action cannot be used for now, not a big deal BTW as I just have to run a command in my end to do the same but could be handy in future to trigger releases from there :)

[vishnureddy17]

I just gave you permissions to the organization, does that work?

[robertsLando]

I saw the email, will give that a look tomorrow. Thanks!