Migrating from sphinx to Material for MkDocs

[DeaMariaLeon]

This is a work in progress in case you want to see locally what I have done. As you know, if you download my branch, one can see the docs locally running mkdocs serve.

Please note that these points are still pending before starting the next step of adding more documentation.

• Cross-reference links.

• The rest of the main rst pages like install, construct, etc, are still missing. But need links fixed

• Some format on the API documents need to be fixed as well. Like the area of the examples.

• Headers, logo, footers need to be added.

• Website needs to be deployed with mkdocs instead of Sphinx

@hameerabbasi @mtsokol

[DeaMariaLeon]

I think I addressed all the requested changes. Please let me know if something is missing.

[DeaMariaLeon]

Thank you @hameerabbasi !