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.

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Signed-off-by: Todd Baert <[email protected]>
Signed-off-by: Tom Carrio <[email protected]>
Signed-off-by: Michael Beemer <[email protected]>
Co-authored-by: Tom Carrio <[email protected]>
Co-authored-by: Michael Beemer <[email protected]>

Author: 3 people