[Documentation] Add clarifying comment to ClosestProof documentation

[h5law]

Summary

Quick PR to add context to the closest proof method

Issue

Fixes N/A

Type of change

Please mark the relevant option(s):

• New feature, functionality or library
• Bug fix
• Code health or cleanup
• Documentation
• Other (specify)

Testing

• Run all unit tests: make test_all
• Run all/relevant benchmarks (if optimising): make benchmark_{all | suite name}

Required Checklist

• I have tested my changes using the available tooling
• I have performed a self-review of my own code
• I have commented my code (godoc format comments see: tip.golang.org/doc/comment)

If Applicable Checklist

• I have added tests that prove my fix is effective or that my feature works
• I have updated any relevant README(s)/documentation and left TODOs throughout the codebase
• Add or update any relevant or supporting mermaid diagrams

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (12d9ac6) 83.28% compared to head (4a984b1) 83.28%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #32   +/-   ##
=======================================
  Coverage   83.28%   83.28%           
=======================================
  Files           8        8           
  Lines        1406     1406           
=======================================
  Hits         1171     1171           
  Misses        178      178           
  Partials       57       57           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[bryanchriswhite]

👆

[bryanchriswhite]

Sorry for continuing to push on such a small thing but I think we're deriving more value by thinking it through.

[bryanchriswhite]

❤️

[Olshansk]

@h5law This is a good addition and on a technical level contains all the details.

However, it's a lot of text & content to parse. For someone with context or who is
willing to sit, think and read this many times, they'll understand. For 99% of OSS
contributors who will be too lazy (think about how many times we dive deep into other's
documentation), I think that bullet points + diagrams will make it easier to understand.

Even I feel like I need to read this multiple times and need to make notes along the way,
and the extra effort to make it easier to read will pay dividends down the road.

If you have time, I recommend approaching it like so.

## ClosestProof Use-Cases

The `CloestProof` function is intended for use in `commit & reveal` mechanism.

_NOTE: Throughout this document, `commitment` of the the tree's hashes is also referred to as closing the tree._

Take the following attack vector (**without** a commit prior to a reveal) into consideration:
1. The prover identifies the hash of a leaf they want to prove
2. The prover (prior to committing) inserts the hash ...
3. ...

Take the following normal flow (**with** a commit prior to reveal) as
1. ...
2.