Added link to code contribution guidelines from application instructions page.

Author: kgodey

content/gsoc-2019/application-instructions/contents.lr

@@ -10,7 +10,7 @@ body:
 
 Take a look at the Creative Commons website to learn more about what we do. Also look at our GitHub organization and our developer community website to get a sense of the code and projects we work on. Making a successful contribution to one of our projects will help us get a sense of your work and is highly recommended.
 
-Read our [Student Expectations](/gsoc-2019/student-expectations) guide.
+Read our [Student Expectations](/gsoc-2019/student-expectations) guide and follow our guidelines when [contributing code](/contributing-code).
 
 ### Applying