Update CONTRIBUTING.md to remove the not about not accepting PR

Author: joker-eph

CONTRIBUTING.md

@@ -5,8 +5,7 @@ contribute, and we appreciate all contributions.
 
 To get started with contributing, please take a look at the
 [Contributing to LLVM](https://llvm.org/docs/Contributing.html) guide. It
-describes how to get involved, raise issues and submit patches. Please note
-that at the moment the LLVM project does not use GitHub pull requests.
+describes how to get involved, raise issues and submit patches.
 
 ## Getting in touch