Add FedRAMP example

[tylercreller]

• Added FedRAMP section to README
• Add FedRAMP values for API URL, Token URL, and Client ID
• Adds an example for FedRAMP authentication

[vkareh]

Looks good to me! Thanks for adding the example file. Does it make sense to link the example file from the README?

[AlexVulaj]

/lgtm

[cristianoveiga]

LGTM