Switch from 'docker-compose' to 'docker compose'. (ros2#3527)

As far as I understand, docker-compose is the V1 version
of the tool (which will stop being supported in June 2023).
'docker compose' is the V2 version of the tool, which
is still supported.

Signed-off-by: Chris Lalancette <clalancette@gmail.com>

source/How-To-Guides/Run-2-nodes-in-single-or-separate-docker-containers.rst

@@ -86,4 +86,4 @@ As an alternative to the command line invocation, you can create a ``docker-comp
        depends_on:
          - talker
 
-To run the containers call ``docker-compose up`` in the same directory. You can close the containers with ``Ctrl+C``.
+To run the containers call ``docker compose up`` in the same directory. You can close the containers with ``Ctrl+C``.