Add comment blocks to about:styles

[luixxiul]

Follow-up to #10978 (comment)

Auditors: @cezaraugusto

Test Plan:

1. Open about:styles

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.

Test Plan:

Reviewer Checklist:

Tests

• Adequate test coverage exists to prevent regressions
• Tests should be independent and work correctly when run individually or as a suite ref
• New files have MPL2 license header

[codecov-io]

Codecov Report

Merging #11522 into master will decrease coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #11522      +/-   ##
==========================================
- Coverage   52.66%   52.62%   -0.04%     
==========================================
  Files         268      268              
  Lines       25218    25218              
  Branches     4022     4022              
==========================================
- Hits        13280    13271       -9     
- Misses      11938    11947       +9

Flag	Coverage Δ
#unittest	52.62% <ø> (-0.04%)	⬇️

Impacted Files	Coverage Δ
js/stores/appStoreRenderer.js	91.17% <0%> (-8.83%)	⬇️
app/renderer/components/reduxComponent.js	84.37% <0%> (-6.25%)	⬇️
js/stores/windowStore.js	27.27% <0%> (-0.31%)	⬇️

[cezaraugusto]

++