Fix typos in documentation

[bmish]

I went through hundreds of potential spelling mistakes flagged by running variations of this cspell command:

cspell "{lib,test,tests}/**/*.{js,ts,md}"

This is not something we can enforce on CI due to the hundreds of false positives from names and other technical API words not in the dictionary. It's worth running manually every once in a while.

I do however recommend the Code Spell Checker extension for VSCode to find mistakes while coding.

[codecov]

Codecov Report

Merging #3366 (11306e1) into master (9836d3a) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #3366   +/-   ##
=======================================
  Coverage   97.54%   97.54%           
=======================================
  Files         123      123           
  Lines        8873     8873           
  Branches     3244     3244           
=======================================
  Hits         8655     8655           
  Misses        218      218           

Impacted Files	Coverage Δ
lib/rules/no-access-state-in-setstate.js	93.75% <ø> (ø)
lib/rules/no-danger.js	100.00% <ø> (ø)
lib/rules/no-direct-mutation-state.js	98.11% <ø> (ø)
lib/rules/no-unescaped-entities.js	100.00% <ø> (ø)
lib/rules/no-unstable-nested-components.js	94.76% <ø> (ø)
lib/rules/prefer-stateless-function.js	87.07% <ø> (ø)
lib/util/Components.js	96.48% <ø> (ø)
lib/util/ast.js	96.39% <ø> (ø)
lib/rules/jsx-curly-brace-presence.js	98.04% <100.00%> (ø)

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