Add user documentation

[jamienoss]

The new docs can be viewed here. Note: some links will not work as expected as they are relative links intended to take you to the host site itself.

Changes:

• This adds a user manual for instructions on how to use the website (from a user perspective).
• When deployed this will host the docs from the live website - it will be completely public though.
• Adds link to docs from landing page.
• Adds link to password reset form from landing page.
• Adds more docstrings.
• Improves API sphinx docs.

Note: I intentionally omitted docs from an admin perspective so as not to expose potential issues.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 90.73%. Comparing base (79ae9cc) to head (f03a8a3).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #337 +/- ## ======================================= Coverage 90.73% 90.73% ======================================= Files 28 28 Lines 2235 2235 ======================================= Hits 2028 2028 Misses 207 207 ``` | [Flag](https://app.codecov.io/gh/RISPaDD/biospecdb/pull/337/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=RISPaDD) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/RISPaDD/biospecdb/pull/337/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=RISPaDD) | `90.73% <100.00%> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=RISPaDD#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[jamienoss]

one overall comment is that some images are quite long, could we find abbreviated versions? Or perhaps there is a way to "ellipsize" them?

I think the only two that are long are the deletion page and the full patient form, both of which I'd like to keep as such to explicitly show their length and content.

[jamienoss]

@amitschang back to you. I made some changes as requested and I've also bulked out the docstrings and API docs.

I would just review the "post review changes" commit by itself, cheers.