Add Documentation for using the config

[swashata]

The purpose of this is to add documentation which is beginner friendly to setup and use ESLint and eslint-config-wordpress for projects.

• [x] Add CLI documentation: Use ESLint from CLI.
• [x] Add VSCode documentation: Use VSCode with eslint-config-wordpress and auto fix.
• [x] Add README.md in docs directory to provide TOC.

/cc @ntwb

[swashata]

@ntwb Please review and let me know if the folder structure is the right way to go. I will change things if needed.

[swashata]

@ntwb I am done with the docs. Please review.

[ntwb]

Apologies for the delay in reviewing this, I'll get stuck into it soon, there is much more here than I was expecting :)

[swashata]

@ntwb no issues at all... I am just investing my company time for three weeks of OSS stuff :) My goal is to learn new ES6, React and WordPress Gutenberg. I am happy to help anywhere I can.

[ntwb]

Thanks a bunch @swashata, I decided to merge this as is, there are a couple of minor tweaks but it will be easier for both of us to merge it as is and iterate from there

Thanks 😄

[swashata]

Great. Thank you. Do let me know if you need me to edit something.