Revise main README for cleanup and some minor clarifications
Created by: wtw
Mainly minor changes to the README file: fixed some typos, added a link and rephrased some sections for (hopefully) a little bit more clarity.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Created by: wtw
Mainly minor changes to the README file: fixed some typos, added a link and rephrased some sections for (hopefully) a little bit more clarity.