HTTP Call-back info
Retry info
Merge pull request #1 from zachmanpro/master

Call-Back Information
Edited the portion about receiving messages

As well as some more minor edits.
Some more polishing and tweaking
Move `token_pay` summary

OK, OK. Redeeming a voucher isn't a popular command; just a useful one for the hackathon. I moved it to the top of the "commonly-used commands" list.
Merge pull request #3 from arnoesterhuizen/master

Documented receiving messages