docs: fix and relocate anonymous-volumes documentation

Anonymous volumes get a bare UUID, not the anon-{uuid} naming
command-reference.md claimed, so its own grep example matched nothing.
Move the fixed explanation into volumes.md alongside the rest of the
volumes docs, and trim command-reference.md to a pointer.

Signed-off-by: Eric Ernst <eric_ernst@apple.com>

Author: egernst

docs/command-reference.md

@@ -911,22 +911,10 @@ container volume create --opt journal=journal --opt size=10g myvolume
 
 **Anonymous Volumes**
 
-Anonymous volumes are auto-created when using `-v /path` or `--mount type=volume,dst=/path` without specifying a source. They use UUID-based naming (`anon-{36-char-uuid}`):
-
-```bash
-# Creates anonymous volume
-container run -v /data alpine
-
-# Reuse anonymous volume by ID
-VOL=$(container volume list -q | grep anon)
-container run -v $VOL:/data alpine
-
-# Manual cleanup
-container volume rm $VOL
-```
-
-> [!NOTE]
-> Unlike Docker, anonymous volumes do NOT auto-cleanup with `--rm`. Manual deletion is required.
+Using `-v /path` or `--mount type=volume,dst=/path` without a source auto-creates a
+named volume for you, tagged with the `com.apple.container.resource.anonymous` label.
+See [Mounts and volumes](./volumes.md#anonymous-volumes) for how to find and clean
+these up.
 
 ### `container volume delete (rm)`
 

docs/volumes.md

@@ -69,11 +69,6 @@ Remove every volume that isn't attached to a container:
 container volume prune
 ```
 
-> [!NOTE]
-> Unlike Docker, anonymous volumes created implicitly by a container do not
-> auto-cleanup when the container is removed with `--rm`. Delete them explicitly with
-> `container volume delete`.
-
 Mount a named volume the same way you bind-mount a host directory, using the volume
 name as the source:
 
@@ -87,6 +82,32 @@ Or with `--mount`:
 container run -it --rm --mount type=volume,source=foo,target=/mnt/foo alpine sh
 ```
 
+## Anonymous volumes
+
+Using `-v /path` or `--mount type=volume,target=/path` without specifying a source
+auto-creates a named volume for you — an anonymous volume. It's named with a bare UUID
+(no prefix) and tagged with the `com.apple.container.resource.anonymous` label:
+
+```bash
+# Creates an anonymous volume
+container run -v /data alpine
+```
+
+Find it by its label (the bare UUID name has no "anon" marker to `grep` for):
+
+```bash
+VOL=$(container volume list --format json | jq -r '.[] | select(.configuration.labels["com.apple.container.resource.anonymous"] != null) | .id')
+container run -v $VOL:/data alpine
+```
+
+> [!NOTE]
+> Unlike Docker, anonymous volumes do **not** auto-cleanup when the container is removed
+> with `--rm`. Delete them explicitly:
+>
+> ```bash
+> container volume rm $VOL
+> ```
+
 ## Named volume mount options
 
 | Option | Values | Description |