Add JSHint and ESLint description.
Add JSHint and ESLint description.

Signed-off-by: Bo-Yi Wu <f80eec1bf98b3feebacc247f35f2b506218004cb@gmail.com>

Shroder/essential-javascript-links,nucliweb/essential-javascript-links,yeion7/essential-javascript-links,yeion7/essential-javascript-links,nucliweb/essential-javascript-links,Shroder/essential-javascript-links