Update CONTRIBUTING.md

Author: floriangbh

CONTRIBUTING.md

@@ -4,7 +4,7 @@ Contributing 🚀
 For fixes, improvements or ideas, fork the repository and issue a pull request.
 
 To get a pull request accepted, please adhere to these rules:
-- Work from the latest `master` branch.
+- Work from the latest `develop` branch.
 - Respect current code style and respect the [SwiftLint](https://github.com/realm/SwiftLint) rules (see swiftlint's file).
 - If this is about new features, please make sure to add enable/disable configuration.