DOC: Add video recording to Selenium

docs/infrastructure/selenium.rst

@@ -7,6 +7,28 @@ We're running our own `Selenium <https://selenium.confirm.ch>`_ Grid service for
 
     The PyPi server is deployed via GitLab CI from the `Selenium project <https://git.confirm.ch/confirm/selenium>`_ and is only available from within private networks. 
 
+Video Recording
+---------------
+
+Our central `Selenium`_ Grid service also supports video recording.
+Just go to the `Selenium Pipelines <https://git.confirm.ch/confirm/selenium/-/pipelines>`_ and do this:
+
+1. Click ``Run Pipeline``
+2. Select the ``master`` branch
+3. Add a new variable ``RECORD`` with either the value ``start`` or ``stop``
+4. Run the pipeline
+
+You can also use this as `GitLab multi-project pipeline <https://docs.gitlab.com/ce/ci/multi_project_pipelines.html>`_ trigger:
+
+.. code-block:: yaml
+
+    Start Recording:
+      variables:
+        RECORD: start
+      trigger:
+        project: confirm/selenium
+        strategy: depend
+
 Selenium Docker Images
 ----------------------