update contributing (#206)

* update contributing

* Update README.md

* Update README.md

---------

Co-authored-by: Michael Paul <michael@michaelpaul.com.br>

CONTRIBUTING.md

@@ -3,7 +3,7 @@
 ## How to contribute step-by-step
 
 1. Fork the `Adyen/adyen-ruby-api-library` repository.
-2. Create a new branch from `develop` in your fork. This makes it easier for you to keep track of your changes.
+2. Create a new branch from `main` in your fork. This makes it easier for you to keep track of your changes.
 3. Make the desired changes to the code.
     * If you are adding new functionality or fixing a bug, we recommend you add unit tests that cover it.
 4. Push the changes to your fork.

README.md

@@ -234,7 +234,7 @@ We value your input! Help us enhance our API Libraries and improve the integrati
 ## Contributing
 
 We encourage you to contribute to this repository, so everyone can benefit from new features, bug fixes, and any other improvements.
-Have a look at our [contributing guidelines](https://github.com/Adyen/adyen-ruby-api-library/blob/develop/CONTRIBUTING.md) to find out how to raise a pull request.
+Have a look at our [contributing guidelines](/CONTRIBUTING.md) to find out how to raise a pull request.
 
 ## Support
 If you have a feature request, or spotted a bug or a technical problem, [create an issue here](https://github.com/Adyen/adyen-ruby-api-library/issues/new/choose).