Add link to code examples in README

[annthurium]

Hello!

First off, thanks for maintaining such a useful library. ❤️ I truly appreciate it.

There is a bunch of really helpful code in the examples folder, that I didn't discover until late in the game. Linking to the examples in the README seems like an easy fix to help other people avoid my mistake. Thanks and have a great day.

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.

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

[childish-sambino]

👍