Chore: rewrite 'npm run update'

[mysticatea]

I realized Uncategorized section is duplicate: README.md.
npm run update seems wrong, but it's difficult to identify the cause.

This PR rewrites the npm run update script to be readable.

• tools/lib/rules.js provides the rule list to be used by update scripts.
• tools/lib/categories.js provides the category list to be used by update scripts.
• tools/update-docs.js updates the header of docs/rules/*.md files.
• tools/update-lib-configs.js updates lib/configs/*.js files.
• tools/update-lib-index.js updates lib/index.js file.
• tools/update-readme.js updates the rule tables of lib/README.md file.

Additionally, this PR changes this internal structure a bit.

• This removes lib/*-rules.js files and npm run update updates lib/configs/*.js directly. Because we don't have lib/config/use-with-caution.js before, but the script seems to make lib/use-with-caution-rules.js if rules exist. This can cause mistakes in future.
• This removes dependency to file system from this plugin. (npm run update updates lib/index.js instead of using require-all at runtime.)
  It will make easy to use this plugin in browsers.

And this PR changes documents a bit:

• This adds a new note into docs/rules/*.md files to show which config includes each rule.
• This adds lacking vue/ prefix to rule IDs in the doc.

[michalsnik]

Amazing ❤️