Add version number to docker run example (#116)

docs/simulator.rst

@@ -405,7 +405,7 @@ To start the app locally, all you'll need is to
 have `Docker <https://www.docker.com/>`_ installed on your computer.
 From there, run this command into a terminal::
 
-    docker run -e BOKEH_ALLOW_WS_ORIGIN=127.0.0.1 -p 8080:8080 oggm/bokeh:20200406 git+https://github.com/OGGM/glacier_simulator.git app.ipynb
+    docker run -e BOKEH_ALLOW_WS_ORIGIN=127.0.0.1 -p 8080:8080 oggm/bokeh:20200406 git+https://github.com/OGGM/glacier_simulator.git@v1.3 app.ipynb
 
 Once running, you should be able to start the app in your browser at this
 address: `http://127.0.0.1:8080/ <http://127.0.0.1:8080/>`_.