basics: Adding cache management commands to examples

content/basics_running_containers.rst

@@ -19,6 +19,8 @@ Let's create the container image with the following command:
 
 .. code-block:: console
 
+   $ mkdir apptainer_cache
+   $ export APPTAINER_CACHEDIR=$PWD/apptainer_cache
    $ apptainer pull python.sif docker://python
 
 We'll talk about container images and image building later on.
@@ -131,7 +133,6 @@ Review of this session
 
 .. admonition:: Key points to remember
 
-
    - You can run the container with ``apptainer run my_image.sif``
    - You can start an interactive shell in a container with ``apptainer shell my_image.sif``
    - You can run a single program in a container with ``apptainer exec my_image.sif my_program arg1 arg2``