Add links to demo github and receiver github

[seanonchain]

At the bottom add a line of text
"The code for this site can be found (on Github) [link=https://github.com/relaycc/receiver-example-cra/] and the integration guide for Receiver is in the Readme (here) [link=https://github.com/relaycc/receiver]"

[BrianS111]

This ticket conflicted a bit with relaycc/receiver#63, but it was the same Idea. There is a PR open for it #3. I followed the specs in the . LMK if anything needs adjustment