Docs: remove duplicate code path analysis document

[mdjermanovic]

Prerequisites checklist

• I have read the contributing guidelines.

What is the purpose of this pull request? (put an "X" next to an item)

[x] Documentation update
[ ] Bug fix (template)
[ ] New rule (template)
[ ] Changes an existing rule (template)
[ ] Add autofixing to a rule
[ ] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:

We have two same documents about code path analysis:

(A) https://github.com/eslint/eslint/blob/master/docs/developer-guide/code-path-analysis.md
(B) https://github.com/eslint/eslint/blob/master/docs/developer-guide/code-path-analysis/README.md

Links in other documents are pointing to (A).

This is (A) on our website: https://eslint.org/docs/developer-guide/code-path-analysis

(B) is actually inaccessible on our website (unless someone adds /index.html to the URL) due to Netlify's default rules which redirect foo/bar/ to foo/bar if there's foo/bar.html file on the server. https://eslint.org/docs/developer-guide/code-path-analysis/ would be (B) but it redirects to (A).

In #14886, we updated only (B). It took me time to figure out why the change doesn't appear on https://eslint.org/docs/8.0.0/developer-guide/code-path-analysis, and then I updated (A) manually on the website (eslint/archive-website#865).

In #14287 we updated both documents with seemingly same changes, but the change in (B) was slightly different and wrong.

Maintaining two documents with the same content is obviously error-prone, so I think we should remove one of them.

What changes did you make? (Give an overview)

• Updated (A) with the latest changes from (B). This should be now the actual version of this document.
• Removed the content in (B), leaving just a link to (A) so that there's a link to the document if someone opens https://github.com/eslint/eslint/tree/master/docs/developer-guide/code-path-analysis folder on GitHub.

Is there anything you'd like reviewers to focus on?

If anyone wants to double-check the final version in (A), I compared (A) and (B) locally and the only differences I could find were:

• Relative links to .svg files (this is expected)
• (A) didn't have the change from Update: Code path analysis for class fields (fixes #14343) #14886
• (A) and (B) had different changes in Chore: Remove lodash #14287, the version in (A) looks good to me.

[nzakas]

LGTM. Nice catch.