GITBOOK-113: update broken links in contribution process (testing practices)

Author: ascourtas

docs/how-to-contribute/contributing.md

@@ -28,7 +28,7 @@ If you want to contribute, start working through the Foundry codebase, navigate
     of the contribution must be compared against the cost of maintaining the
 
     feature.
-* Tests should follow [testing best practices](https://www..org/community/contribute/tests) guide.
+* Tests should follow [Pythonic testing best practices](https://www.w3resource.com/python-interview/what-are-the-common-testing-best-practices-in-python.php) and utilize the [pytest framework](https://realpython.com/pytest-python-testing/) 
 
 ## Pull Request Process