Merge pull request #171 from RRosio/playwright_dev_docs

Updating contributing docs for playwright tests

Author: echarles

Diff for: CONTRIBUTING.rst

@@ -133,6 +133,14 @@ To run the Python tests, use::
 
     pytest
 
+For the end to end Pytest-Playwright tests you will need to install the browser binaries using::
+
+    playwright install
+    
+Then you can run the end to end tests using::
+    
+    pytest -sv nbclassic/tests/end_to_end
+
 If you want coverage statistics as well, you can run::
 
     py.test --cov nbclassic -v --pyargs nbclassic