Update exampleUsage.js

- updated descriptions of parameters
- added "showImages" and "lang" parameters
- edited manual to create valid ID and use TwitterFetcher
- made it match JSDoc
Tidied up some brackets which should be []

Made square brackets and changed types for function only (string was from the days when we didnt have an object to configure).
Merge pull request #9 from dvorapa/patch-2

Update exampleUsage.js to JSDoc comments.