Tox reference (#211)

* Use a better link to the tox project

* Use a better link to the tox project

* Use a better link to the tox project

README.md

@@ -80,7 +80,7 @@ The directory structure of your new project looks like this:
 │   └── visualization  <- Scripts to create exploratory and results oriented visualizations
 │       └── visualize.py
 │
-└── tox.ini            <- tox file with settings for running tox; see tox.testrun.org
+└── tox.ini            <- tox file with settings for running tox; see tox.readthedocs.io
 ```
 
 ## Contributing

docs/docs/index.md

@@ -120,7 +120,7 @@ cookiecutter https://github.com/drivendata/cookiecutter-data-science
 │   └── visualization  <- Scripts to create exploratory and results oriented visualizations
 │       └── visualize.py
 │
-└── tox.ini            <- tox file with settings for running tox; see tox.testrun.org
+└── tox.ini            <- tox file with settings for running tox; see tox.readthedocs.io
 ```
 
 ## Opinions

{{ cookiecutter.repo_name }}/README.md

@@ -49,7 +49,7 @@ Project Organization
     │   └── visualization  <- Scripts to create exploratory and results oriented visualizations
     │       └── visualize.py
     │
-    └── tox.ini            <- tox file with settings for running tox; see tox.testrun.org
+    └── tox.ini            <- tox file with settings for running tox; see tox.readthedocs.io
 
 
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