Update hacking docs about docker usage

doc/hacking/using-docker.rst

@@ -23,11 +23,15 @@ Building the Docker image
 
 First you will need to obtain the NAV source code.
 
-The source contains a configuration file for `Docker Compose`_ to build a
-suite of containers for PostgreSQL, Graphite and NAV itself. Simply run this
-command to build and run everything::
+The source contains a configuration file for `Docker Compose`_ to build a suite
+of containers for PostgreSQL, Graphite and NAV itself.  These definitions
+contain everything needed to run and develop NAV directly from the checked out
+source code.
 
-    docker-compose up
+In order to build the container images successfully the first time, use this
+command::
+
+    make docker
 
 .. Tip:: The first time you run this would be the perfect time to grab some
          coffee (and maybe redecorate your living room), as the initial build
@@ -37,12 +41,16 @@ command to build and run everything::
 Using the container(s)
 ----------------------
 
-The Docker Compose specificiation creates these containers (called "services"
-in Docker Compose lingo):
+The Docker Compose specificiation creates several containers (called "services"
+in Docker Compose lingo).  Several of them will mount the checked out source
+code directory internally on the `/source` directory, allowing them to always
+be up-to-date with the latest changes you are making in your favorite editor.
+
+These are the defined services:
 
 nav
   This container runs the NAV backend processes and cron jobs. It also runs the
-  "sass-watcher" job, which will watch ``*.scss`` files for modifications and
+  ``sass-watcher`` job, which will watch ``*.scss`` files for modifications and
   recompile NAV's CSS when changes do occur.
 
 web
@@ -74,21 +82,21 @@ NAV daemons using the ``nav`` command, adjust the running config, or whatever)
 by running a bash shell inside the container, like so (for the ``nav``
 container)::
 
-  docker-compose exec nav /bin/bash
+  docker compose exec nav /bin/bash
 
 Manually restarting the web server
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 To manually restart the web server, all you need is::
 
-  docker-compose restart web
+  docker compose restart web
 
 Rebuilding the NAV code from scratch
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 A complete rebuild of the NAV code can be initiated by::
 
-  docker-compose restart nav
+  docker compose restart nav
 
 Rebuilding the containers
 ~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -98,7 +106,17 @@ images the containers are based on (as different development branches may have
 different requirements, and therefore different Dockerfiles). Stop the existing
 containers and run this::
 
-  docker-compose build
+  docker compose build --build-arg UID=$UID --build-arg GID=$GID
+
+The ``UID`` and ``GID`` arguments are there to ensure that the unprivileged
+user created inside the container will match your user's UID and GID on your
+local system, so that any files the containers create in the mounted source
+code directories are owned by you, and not by some other user id (like
+``root``).
+
+A quicker rebuild can be achieved by :kbd:``make docker``: This will
+automatically fetch your ``UID`` and ``GID`` and insert them into the above
+command.
 
 
 Controlling processes inside the nav container