Add readthedocs page for mapca

[eurunuela]

Closes#42 .

This PR adds the documentation related to the package.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.42%. Comparing base (0ae41bb) to head (1e8a8db).
⚠️ Report is 34 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #46 +/- ##
=======================================
Coverage 90.42% 90.42% =======================================
Files 3 3 Lines 282 282 =======================================
Hits 255 255 Misses 27 27 

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[handwerkerd]

Great start! My one general comment is that, as a learning tool, it would be nice to have a few more "why" comments instead of the current "what" comments. That is, you include things like "Step 2: Apply kurtosis threshold of Gaussianity to SVD data to get first estimate of subsampling depth" without saying why this step is happening. This doesn't have to be a textbook level of detail, but a sentence or two at the beginning of each code block explain why each step is done would help.