Updated Readme

A few changes:
1. I left the provisions to install a super-cap, however FRAM IC makes dealing with power outages a lot easier. It has the same endurance and speed as regular SRAM, but retains state during power interruptions. LIPO is in no way economical, and will bump up the cost at least 20$ per unit. I think we discussed this in a meeting few months ago.
2. Using dual transformers is how we made G1 work in the end. In G2 we forgo the transformers and work with line voltages directly, hence the need for this review.

The rest is just tidying up.