Update CONTRIBUTING.md

Author: webron

CONTRIBUTING.md

@@ -1,7 +1,3 @@
-## Pull Requests
-Please open your pull requests against the [**`develop_2.0`**](https://github.com/swagger-api/swagger-ui/tree/develop_2.0) branch at this time.
-
-## Issues
 SwaggerUI uses [SwaggerJS](https://github.com/swagger-api/swagger-js) library for many internal operations. If you see errors in
 [`swagger-client.js`](lib/swagger-client.js) file, you should probably open the issue in [SwaggerJS](https://github.com/swagger-api/swagger-js) repository.