Copy readme contents to documentation project

[Raithlin]

The creation of the Package Reference pages that replace the readme.md details.

[warriordog]

@Raithlin Great work, thank you! I do have a couple of requests:

1. Could we move these to the "User Guide" section instead of "Dev Resources"? And maybe even add a sub-section to group them, like "Package Reference" or something.
2. Would you additionally replace the original files (in the code area) with just a header and a link to these new documentation files?

[Raithlin]

@warriordog I think I got this right, but without a local setup to mirror the github.io docs I can't be sure. I may need to rename the Package Reference folder to Package_Reference or similar.

[warriordog]

@Raithlin sorry for not responding - I've been very busy recently. You can test locally by running docfx docfx.json --serve from the documentation folder. (side note - I should add that in the documentation somewhere.)

[warriordog]

Looks great, thank you!