Update documentation for SA1413 to include rationale

[sharwell]

Closes #2416

[codecov]

Codecov Report

Merging #2418 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2418      +/-   ##
==========================================
- Coverage   96.46%   96.44%   -0.02%     
==========================================
  Files         714      714              
  Lines       92517    92517              
  Branches     3443     3443              
==========================================
- Hits        89242    89224      -18     
- Misses       2384     2401      +17     
- Partials      891      892       +1

Impacted Files	Coverage Δ
...eCop.Analyzers/Helpers/ObjectPools/ObjectPool`1.cs	57.4% <0%> (-33.34%)	⬇️

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