You-Dont-Know-JS

es6+beyond: ch2, corrected typo

es6+beyond: ch2, added the huge, hairy 'unicode' section, thanks to @mathias for amazing info

es6+beyond: adding some clarifications about unicode-regexes and note about @mathias' expertise on the subject

es6+beyond: ch2, adding note about 'RegExp' overriding 'flags', per @allenwb

es6+beyond: ch2, 'number literal extensions' section