docs: overhaul readme

[madflow]

This PR contains a:

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

Motivation / Use-Case

This PR tries to make the README a more pleasant read.

• Added YARN setup
• Webpack as proper nount
• sass-loader whenever it is used
• Some small fixes with good intentions

[jsf-clabot]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #771 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #771   +/-   ##
=======================================
  Coverage   97.75%   97.75%           
=======================================
  Files          10       10           
  Lines         178      178           
  Branches       63       63           
=======================================
  Hits          174      174           
  Misses          4        4

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[alexander-akait]

Good job, remove yarn section from this PR, we use template for README and need added this section in template (improve all readme in future)

[madflow]

Done and rebased.

[alexander-akait]

Thanks for PR, good job!