tox: add page (#2225)

pages/common/tox.md

@@ -0,0 +1,24 @@
+# tox
+
+> Automate Python testing across multiple Python versions.
+> Use tox.ini to configure environments and test command.
+
+- Run tests on all test environments:
+
+`tox`
+
+- Create a tox.ini configuration:
+
+`tox-quickstart`
+
+- List the available environments:
+
+`tox --listenvs-all`
+
+- Run tests on a specific environment (e.g. python 3.6):
+
+`tox -e {{py36}}`
+
+- Force the virtual environment to be recreated:
+
+`tox --recreate -e {{py27}}`