Improve documentation

[juanep97]

This PR improves the documentation, adding several notebook examples.

The notebooks are implemented in 'pct' format, a fully text-based and human-readable format that is also valid Python code. They are automatically converted from pct format to usual ipynb by jupytext and executed by MyST-NB. They can be browsed as part of the normal documentation, they are integrated in the Sphinx docs through:

extensions = [
    'myst_nb',
    "nbsphinx",
]

...

nb_custom_formats = {
    '.py': ['jupytext.reads', {'fmt': 'py:percent'}],
}

It also documents how to set up IOP4 for production (in a public server).

As of now the docs use the test dataset and catalog.

[juanep97]

@morcuended what do you recommend between available options (.ipynb + nbspinx, .myst + myst_nb, .py + sphinx-gallery)?

[morcuended]

maybe sphinx-gallery?

[morcuended]

so what's the problem with the downloading of test data? does it have a new checksum?

[juanep97]

so what's the problem with the downloading of test data? does it have a new checksum?

It didn't set the credentials and checksum right, I think it will be solved in this CI run.

[juanep97]

If these the tests pass, I think it is good enough for now. We can keep improving the docs in other PRs with more example notebooks, etc.

[morcuended]

Sure, this is good to go already. Great job