NEXT-32769 - Update CONTRIBUTING.md

Fix links and grammar tweaks
fixes shopware#3479

CONTRIBUTING.md

@@ -1,12 +1,12 @@
 # Get involved
 
-Shopware is available under MIT license. If you want to contribute code (features or bugfixes), you have to create a pull request and include valid license information. Contribute your code under MIT license.
+Shopware is available under MIT license. If you want to contribute code (features or bug fixes), you have to create a pull request and include valid license information. Contribute your code under MIT license.
 
 If you want more details about available licensing or the contribution agreements we offer, you can contact us at <[email protected]>.
 
 ## Contributing to the Shopware code base
-If you want to learn how to contribute code to Shopware, please refer to [Contributing Code](https://docs.shopware.com/en/shopware-platform-dev-en/contribution/contributing-code?category=shopware-platform-dev-en/contribution).
-Also make sure that you add a changelog file which describes your changes in a meaningful way. For more information refer to [this document](https://github.com/shopware/platform/blob/trunk/adr/workflow/2020-08-03-implement-New-Changelog.md).
+If you want to learn how to contribute code to Shopware, please refer to [Contributing Code](https://developer.shopware.com/docs/resources/guidelines/code/contribution.html).
+Also, make sure that you add a changelog file that describes your changes in a meaningful way. For more information refer to [this document](https://github.com/shopware/shopware/blob/trunk/adr/2020-08-03-implement-new-changelog.md).
 
 ## Documentation