add how to contribute on readme

Author: SDSTony

README.md

@@ -1,2 +1,13 @@
 # Deep Learning Tutorials using PyTorch (PseudoLab)
 
+
+
+## How to contribute
+
+1. fork [Pseudo-Lab/Tutorial-Book](https://github.com/Pseudo-Lab/Tutorial-Book)
+2. clone the forked repo to your local computer
+3. make necessary changes on the local repo
+4. push the changes made on the local repo to the forked repo
+5. create a pull request from the forked repo to [Pseudo-Lab/Tutorial-Book](https://github.com/Pseudo-Lab/Tutorial-Book)
+6. Repeat step 3 and 5
+