DOC: Dead link for setup.html

[abel-bzz]

What happened:

In the documentation, the links to https://distributed.dask.org/en/latest/setup.html go into a 404 error.
In fact, setup.html redirect to https://docs.dask.org/en/latest/how-to/deploy-dask-clusters which seems to miss the ".html" to its end, which causes the 404.

What you expected to happen:
Proper redirection.

Minimal Complete Verifiable Example:

1. Go to https://distributed.dask.org/en/latest/quickstart.html
2. Click the link in See setup documentation for advanced use.

Anything else we need to know?:
I couldn't find an existing issue about this, sorry if it has already been spotted.

Environment:

• Dask version: latest
• Python version: N/A
• Operating System: N/A
• Install method (conda, pip, source): N/A

[fjetter]

@bzah thank you very much for the report. we recently changed our sphinx theme and i believe this slipped through. This is a wrong redirect in the dask/dask repo, see dask/dask#8249