docs: update order of headings to be semantically correct

[mnigh]

These changes ensures that headings are in a logical order in several files using markdown.

For example, the heading level following an h1 element should be an h2 element, not an h3 element.

source: https://dequeuniversity.com/rules/axe/4.4/heading-order

[xDivisionByZerox]

Can you provide a description that explains the change you did here? If possible, link to some sources about "semantically correct HTML".

[codecov]

Codecov Report

Merging #1335 (fc95249) into main (bf1ea09) will increase coverage by 0.00%.
The diff coverage is n/a.

❗ Current head fc95249 differs from pull request most recent head aed746f. Consider uploading reports for the commit aed746f to get more accurate results

@@           Coverage Diff           @@
##             main    #1335   +/-   ##
=======================================
  Coverage   99.62%   99.63%           
=======================================
  Files        2163     2163           
  Lines      240701   240701           
  Branches     1014     1018    +4     
=======================================
+ Hits       239794   239818   +24     
+ Misses        886      862   -24     
  Partials       21       21           

Impacted Files	Coverage Δ
src/modules/internet/user-agent.ts	88.09% <0.00%> (+6.34%)	⬆️

[ST-DDT]

Is this worth adding an eslint rule(s)?