docs(patch): Add "About Percentiles" page

[finestructure]

Description

Adds a new documentation page about percentiles and how to interpret them.

How Has This Been Tested?

Generated the docs locally in Xcode.

Minimal checklist:

• I have performed a self-review of my own code
• I have added DocC code-level documentation for any public interfaces exported by the package
• I have added unit and/or integration tests that prove my fix is effective or that my feature works

[finestructure]

@hassila , as discussed I've taken a stab at extending the docs with a little more info about percentiles and the like.

I feel like the last section "Interpreting results" could have a little more to it but I struggled to come up with anything other than what I've got. I recall from watching Gil Tene's talks that there should be something about focusing on the worst value but I'm unsure how to phrase that (or even if that's always the best thing to do).

Hope that helps regardless!

[hassila]

This is awesome, thanks @finestructure - much appreciated!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (2b704b1) 67.18% compared to head (ec59ca7) 67.18%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #221   +/-   ##
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  Coverage   67.18%   67.18%           
=======================================
  Files          34       34           
  Lines        4376     4376           
=======================================
  Hits         2940     2940           
  Misses       1436     1436           

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[hassila]

Very nice, thanks again!