Update readme for eslint

[jonaskello]

Fixes #1

[codecov-io]

Codecov Report

Merging #2 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master       #2   +/-   ##
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  Coverage   90.51%   90.51%           
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  Files          22       22           
  Lines         369      369           
  Branches       56       56           
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  Hits          334      334           
  Misses         26       26           
  Partials        9        9

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[jonaskello]

Looking into how they do docs over at typescript-eslint I found this line. It seems they call the eslint-docs tool there. However it is not installed as part of their monorepo. I tried to clone that repo and run npm run docs in packages/eslint-plugin but it gives an error that there is no lib folder. I'm not sure they are actually using this tool anymore. There is also some code to verify the readme here.

I think I'll do the table for the rules manually for now and the we can look into automating it later.

[jonaskello]

Note that this PR will only port the readme file to eslint and split out all the rule docs to separate files. It does not fix each rule doc, they will be ported in a future PR.