Move documentation to twilio.com/docs/authy/api

[robinske]

Updates the README to be consistent with other Twilio supported helper libraries for Authy.

See: https://www.twilio.com/docs/authy/api/applications https://www.twilio.com/docs/authy/api/users https://www.twilio.com/docs/authy/api/one-time-passwords https://www.twilio.com/docs/authy/api/push-authentications

Also moves Verify V1 docs to a legacy readme and guides folks towards V2 of Verify

Contributing to Twilio

All third-party contributors acknowledge that any contributions they provide will be made under the same open-source license that the open-source project is provided under.

• [x] I acknowledge that all my contributions will be made under the project's license.

[codecov-io]

Codecov Report

Merging #62 into master will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #62   +/-   ##
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  Coverage   73.61%   73.61%           
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  Files          23       23           
  Lines         921      921           
  Branches       95       95           
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  Hits          678      678           
  Misses        202      202           
  Partials       41       41