Dev.ej/prep for mkdocs

[joanise]

PR Goal?

Add a link to the old Sphinx base documentation to point to the new location.

While I'm here, fix two syntactic errors so the latest version on https://readalong-studio.readthedocs.io/ will display correctly. (I had to fix them for the convert to .md to work correctly.)

Fixes?

Prepares the way for #213 Related to #223

Feedback sought?

sanity checking

Priority?

normal

Tests added?

n/a

How to test?

locally build and examine the docs:

cd docs
pip install -r requirements.txt
make html    # or: sphinx-build -M html . _build
cd _build/html
python -m http.server

then navigate to http://127.0.0.1:8000 and see: then make sure the link forward to the new docs is good.

Confidence?

high

Version change?

no

Required follow-up action

@roedoejet Once we merge this we'll need to do a final documentation push to readthedocs and make sure https://readalong-studio.readthedocs.io/en/latest/ gets updated with the forward link.

[codecov[bot]]

Codecov Report

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

Project coverage is 87.23%. Comparing base (396b2f1) to head (a80c35e).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #224 +/- ## ========================================== - Coverage 87.45% 87.23% -0.23% ========================================== Files 21 21 Lines 1770 1770 Branches 321 321 ========================================== - Hits 1548 1544 -4 - Misses 186 189 +3 - Partials 36 37 +1 ```

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