Update to Contributions (google#87)

* updates to existing contributions page and linking it in the main README

* remove trailining whitespaces

* clarified guidelines in contributions

Author: kshiteejm

README.md

@@ -22,6 +22,9 @@ Gradient.
 For more details about MLGO, please refer to our paper
 [MLGO: a Machine Learning Guided Compiler Optimizations Framework](https://arxiv.org/abs/2101.04808).
 
+For more details about how to contribute to the project, please refer to
+[contributions](docs/contributing.md).
+
 ## Pretrained models
 
 We occasionally release pretrained models that may be used as-is with LLVM.

docs/contributing.md

@@ -1,7 +1,12 @@
 # How to Contribute
 
-We'd love to accept your patches and contributions to this project. There are
-just a few small guidelines you need to follow.
+We'd love to accept your patches and contributions to this project. A good
+starting step to get familiar with the project and set up a development
+enviroment as per [demo](docs/demo/demo.md). After running through the demo, a
+good second step is to pick up an open
+[issue](https://github.com/google/ml-compiler-opt/issues) or create one that you
+would like to work on and submit a patch for. Please make sure that your patch
+adheres to all the guidelines given below.
 
 ## Contributor License Agreement