Add documentation and references to the Calculations code

[bujowskis]

• [x] find and add the materials (in general + code)
• [x] let us know
• [x] @white07S add high-level explanations and relevant, "explicit" links (codeReview/sup_res, etc. - it's nice to keep it throughout the whole project)

[bujowskis]

@white07S is this commit the explanations?

also, what's up with cython and the changes in the testing (in the commit here)

[white07S]

@bujowskis Indded this commit is the explanations for those calculations.

I am not sure why Cython automatically created that file but I will try to fix it asap.

[bujowskis]

@white07S I mean, I'm not sure if there's anything wrong they are being created, the question is - should cython be committed?

also, did you check and make sure the learn_code.py stuff runs and works for you? It throws some errors, as if no data was found for any of the tickers provided

- AMD: No data found for this date range, symbol may be delisted

and then the index is out of bounds for iloc

I'm not sure if that's just me or there's sth wrong with the code you've commited, let me know

[bujowskis]

@white07S also, there seem to have risen some errors with the imports/structure and the tests are failing?