Add doc fix for all-in-one in venv

When running in virtual environment a bootstrapping task will
install 'docker' python module in the environment. After that
prechecks and deploy phase will not find the module because
their 'ansible interpreter' is host wide. With this fix it is
advised to set an interpreter to the one in virtual environment

Closes-Bug: #1969812
Change-Id: I1bb6a3af3fa6346fff0a262e0c53d12c544f46db

doc/source/user/quickstart.rst

@@ -202,6 +202,13 @@ Install Kolla-ansible for deployment or evaluation
 
       cp /path/to/venv/share/kolla-ansible/ansible/inventory/* .
 
+   For ``all-in-one`` scenario in virtual environment add the following
+   to the very beginning of the inventory:
+
+   .. code-block:: console
+
+      localhost ansible_python_interpreter=python
+
    If not using a virtual environment, run:
 
    .. code-block:: console