Fix doc links in README.md

Documentation links to the wrong page in the README.md - this PR fixes that.

README.md

@@ -14,15 +14,15 @@ composer require --dev 10up/wp_mock
 
 ## Documentation
 
-Learn more about how to configure and how to use WP_Mock by reading [the WP_Mock documentation](https://wp-mock.gitbook.io/documentation/general/introduction).
+Learn more about how to configure and how to use WP_Mock by reading [the WP_Mock documentation](https://wp-mock.gitbook.io/documentation/getting-started/introduction).
 
 ## Contributing
 
 Please read our [Code of Conduct](https://github.com/10up/wp_mock/blob/trunk/CODE_OF_CONDUCT.md) for details on our code of conduct, and our [Contributing Guidelines](https://github.com/10up/wp_mock/blob/trunk/CONTRIBUTING.md) for details on the process for submitting pull requests.
 
 ## Supporters
 
-WP_Mock is supported by [10up](https://10up.com) and [GoDaddy](https://godaddy.com). [GitBook](https://www.gitbook.com/) kindly offers free hosting for [WP_Mock documentation](https://wp-mock.gitbook.io/documentation/general/introduction).
+WP_Mock is supported by [10up](https://10up.com) and [GoDaddy](https://godaddy.com). [GitBook](https://www.gitbook.com/) kindly offers free hosting for [WP_Mock documentation](https://wp-mock.gitbook.io/documentation/getting-started/introduction).
 
 A special thanks to all [WP_Mock contributors](https://github.com/10up/wp_mock/graphs/contributors).
 
@@ -34,4 +34,4 @@ A special thanks to all [WP_Mock contributors](https://github.com/10up/wp_mock/g
 [packagist-image]: https://img.shields.io/packagist/dt/10up/wp_mock.svg
 [packagist-url]: https://packagist.org/packages/10up/wp_mock
 [coveralls-image]: https://coveralls.io/repos/github/10up/wp_mock/badge.svg?branch=trunk
-[coveralls-url]: https://coveralls.io/github/10up/wp_mock?branch=trunk
+[coveralls-url]: https://coveralls.io/github/10up/wp_mock?branch=trunk