feat!: Address descriptors

[tcliff111]

Thank you for opening a Pull Request!

---

Before submitting your PR, there are a few things you can do to make sure it goes smoothly:

• [x ] Make sure to open a GitHub issue as a bug/feature request before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea
• [ x] Ensure the tests and linter pass
• [x ] Code coverage does not decrease (if any source code was changed)
• [ x] Appropriate docs were updated (if necessary)

Fixes #294 🦕

[tcliff111]

• Let's update the README "Usage" section with either a demonstration of Geocoding or a pointer to see examples by examining tests.
• Does https://github.com/googlemaps/google-maps-services-go/blob/master/examples/geocoding/cmdline/main.go need to be updated as well?

Just updated the README and also updated the main.go file.