Can we move all the Word and README information into Doxygen?

[terrillmoore]

It's pretty tedious maintaining the Word file documentation. Similarly, the gigantic README now has important documentation that probably would be better in a Doxygen-style set of pages. It would be agreeable to reorganize all this.

Some things, like the "LoRaWAN at a glance" chart, might want to go to separate repos, as they're not really LMIC related.