docs: update readme with additional info on test functions obfuscation

[vetalapo]

Description

This pull request is a follow up on discussion on Discord -> Some students had concerns regarding lightly obfuscated functions in the Test Suite.

Type of change

Added a new section in README.md addressing possible concerns.
Described reasoning behind obfuscations.

P.S.: Couldn't find contribution guidelines. If this kind of update is needed, can do updates for the rest of the test tasks which contain obfuscation.

[MikAleinik]

Thanks for the proposed additions!
I believe that students should have no need to understand what exactly is hidden behind obfuscated code. And in a simple version its use is limited.
A student's use of a solution in obfuscated code from the assignment is equivalent to using any other ready-made solution.
@valerydluski please have your say on this issue

[valerydluski]

I don't think we need it.

[vetalapo]

I made this PR because if this:

I had a feeling that it's going to fall through.

Well alright, you guys have to come up with an explainer somewhere then, why there's a need in obfuscated code for students' tasks and what exactly it does. Alternately remove portions of such code, or make tests part of https://app.rs.school/

See, it's pretty daunting to spin up a virtual machine / docker container every time I need to do a coding test. Because there is no way I trust that code or platform, especially after commentary I get here.