Support generating sphinx doc

[allemangD]

Notable changes I've made since @jcfr's contributions:

• Migrated content from the Wiki and some PRs to the documentation (see fa60c31)
• Cleared that documentation from the github wiki; so the wiki could be disabled once these changes are published
• Switched to MyST markdown parser, mentioned in https://github.com/BICCN/cell-locator/issues/162#issuecomment-852458054, and converted all existing docs to markdown.

One note regarding MyST - if we ever want to do reference-style documentation of the classes (see pillow's api reference, for example), we will still have to use reStructuredText. These types of docs use one or both of sphinx.ext.autodoc and sphinx python domain, neither of which is supported by MyST. I began creating such documentation to replace this code block and ran into the issue.

Docs are published at https://cell-locator.readthedocs.io/en/support-generating-sphinx-doc/

Resolves #162.

[allemangD]

Also worth noting there is a sphinx c++ domain for reference documentation; this also requires use of reST, and I don't think there is any autodoc available like for Python.

[allemangD]

There is a workaround to render reference docs and autodoc, mentioned here; enclose the problematic section in an eval-rst directive.

https://github.com/executablebooks/MyST-Parser/issues/163#issuecomment-679907892

[jcfr]

and I don't think there is any autodoc available like for Python

Indeed. That said, there is the possibility to integrate with doxygen using https://breathe.readthedocs.io/en/latest/

[jcfr]

I updated the readthedocs settings and the currently active version is now "latest" see https://cell-locator.readthedocs.io/en/latest/ and https://cell-locator.readthedocs.io