Allow inline CSS in docs

[jolheiser]

The heading anchors use inline CSS, so changing this will stop the console CSP errors and style them the same green color our other links use.

Current:

After:

[codecov-io]

Codecov Report

Merging #9349 into master will increase coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #9349      +/-   ##
==========================================
+ Coverage   41.26%   41.27%   +<.01%     
==========================================
  Files         561      561              
  Lines       73439    73439              
==========================================
+ Hits        30307    30312       +5     
+ Misses      39338    39331       -7     
- Partials     3794     3796       +2

Impacted Files	Coverage Δ
modules/migrations/migrate.go	23.4% <0%> (-1.6%)	⬇️
modules/migrations/gitea.go	8.84% <0%> (-0.64%)	⬇️
models/repo.go	47.92% <0%> (-0.05%)	⬇️
models/error.go	34.5% <0%> (+1.17%)	⬆️
modules/process/manager.go	78.31% <0%> (+3.61%)	⬆️
modules/task/migrate.go	28.94% <0%> (+3.94%)	⬆️

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[guillep2k]

It's not the subject of this PR, but the tea cup color seems a little blueish.

[jolheiser]

It's not the subject of this PR, but the tea cup color seems a little blueish.

It just uses currentColor, which ends up being the color of links.