Adding contribution guidelines (#3)

Signed-off-by: Ruyman Reyes <ruyman@codeplay.com>

Author: Ruyk

Contributing.md

@@ -0,0 +1,12 @@
+Contributing
+-------------
+
+New examples or improvements to the existing ones are welcomed. 
+Please, follow 
+[LLVM coding standards](https://llvm.org/docs/CodingStandards.html) when 
+contributing code, since sometimes they will be contributed as tests to the
+[DPCPP project](https://github.com/intel/llvm) project.
+
+When writing your commit message, please make sure to follow 
+[LLVM developer policies](https://llvm.org/docs/DeveloperPolicy.html#commit-messages) 
+on the subject.