docs: remove depreciated extract-text-webpack-plugin

[snitin315]

This PR contains a:

• bugfix
• new feature
• code refactor
• test update
• typo fix
• metadata update

Motivation / Use-Case

For webpack/webpack.js.org#3776

Refers webpack/webpack.js.org#3776 (comment)

Breaking Changes

Additional Info

[codecov]

Codecov Report

Merging #539 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #539   +/-   ##
=======================================
  Coverage   88.49%   88.49%           
=======================================
  Files           5        5           
  Lines         426      426           
  Branches       94       94           
=======================================
  Hits          377      377           
  Misses         47       47           
  Partials        2        2           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b21c137...ec687dd. Read the comment docs.

[alexander-akait]

Thanks!

[EugeneHlushko]

@evilebottnawi This should be safe to merge regardless right?

[alexander-akait]

@EugeneHlushko yes, I will fix CI tomorrow and do merge

[alexander-akait]

Thanks