Mention bind-mounting plugins dir in Docker docs (#82622)

Closes #69533.

The Docker docs mention bind-mounting the `config`, `data` and
`logs` directories when using an arbitrary UID / GID, but they fail
to mention that the `plugins` dir must also be mounted in order to
install plugins.

docs/reference/setup/install/docker.asciidoc

@@ -141,10 +141,10 @@ start the new node with the generated enrollment token.
 --
 .Generating enrollment tokens
 ****
-The enrollment token is valid for 30 minutes. If you need to generate a 
+The enrollment token is valid for 30 minutes. If you need to generate a
 new enrollment token, run the
 <<create-enrollment-token,`elasticsearch-create-enrollment-token`>> tool on your
-existing node. This tool is available in the {es} `bin` directory of the Docker 
+existing node. This tool is available in the {es} `bin` directory of the Docker
 container.
 
 For example, run the following command on the existing `es01` node to
@@ -158,7 +158,7 @@ docker exec -it es01 /usr/share/elasticsearch/bin/elasticsearch-create-enrollmen
 --
 
 . In the terminal where you started your first node, copy the generated
-enrollment token for adding new {es} nodes. 
+enrollment token for adding new {es} nodes.
 
 . On your new node, start {es} and include the generated enrollment token.
 +
@@ -445,11 +445,17 @@ chmod g+rwx esdatadir
 chgrp 0 esdatadir
 --------------------------------------------
 
-You can also run an {es} container using both a custom UID and GID. Unless you
-bind-mount each of the `config`, `data` and `logs` directories, you must pass
-the command line option `--group-add 0` to `docker run`. This ensures that the user
-under which {es} is running is also a member of the `root` (GID 0) group inside the
-container.
+You can also run an {es} container using both a custom UID and GID. You
+must ensure that file permissions will not prevent {es} from executing. You
+can use one of two options:
+
+* Bind-mount the `config`, `data` and `logs`
+  directories. If you intend to install plugins and prefer not to
+  <<_c_customized_image, create a custom Docker image>>, you must also
+  bind-mount the `plugins` directory.
+* Pass the `--group-add 0` command line option to `docker run`. This
+  ensures that the user under which {es} is running is also a member of the
+  `root` (GID 0) group inside the container.
 
 ===== Increase ulimits for nofile and nproc