chore: update README for web site inclusion (#104)

This PR:

- updates the README based on latest template for automatic inclusion in
http://openfeature.dev/

I've tried to get everything right, but there's 5-6 code-example TODOs.

@beeme1mr feel free to make any corrections you see. Up to you if you
think we can include this without the code samples.

---------

Signed-off-by: Todd Baert <todd.baert@dynatrace.com>
Signed-off-by: Tom Carrio <tom@carrio.dev>
Signed-off-by: Michael Beemer <beeme1mr@users.noreply.github.com>
Co-authored-by: Tom Carrio <tom@carrio.dev>
Co-authored-by: Michael Beemer <beeme1mr@users.noreply.github.com>