docs: Revise watchtower page (#3583)

- Better clarify images are only updated to newer image updates to the same tag of the running container(s).
- Slight revisions to existing content.

docs/content/config/advanced/maintenance/update-and-cleanup.md

@@ -6,6 +6,8 @@ title: 'Maintenance | Update and Cleanup'
 
 !!! example "Automatic image updates + cleanup"
 
+    Run a `watchtower` container with access to `docker.sock`, enabling the service to manage Docker:
+
     ```yaml title="compose.yaml"
     services:
       watchtower:
@@ -17,26 +19,35 @@ title: 'Maintenance | Update and Cleanup'
           - /var/run/docker.sock:/var/run/docker.sock
     ```
 
+!!! tip "The image tag used for a container is monitored for updates (eg: `:latest`, `:edge`, `:13`)"
+
+    The automatic update support is **only for updates to that specific image tag**.
+
+    - Your container will not update to a new major version tag (_unless using `:latest`_).
+    - Omit the minor or patch portion of the semver tag to receive updates for the omitted portion (_eg: `13` will represent the latest minor + patch release of `v13`_).
+
 !!! tip "Updating only specific containers"
 
-    The default `watchtower` service will check every 24 hours for any new image updates to pull, **not only the images** defined within your `compose.yaml`.
+    By default the `watchtower` service will check every 24 hours for new image updates to pull, based on currently running containers (_**not restricted** to only those running within your `compose.yaml`_).
 
-    The images to update can be restricted with a custom command that provides a list of containers names and other config options. Configuration is detailed in the [`watchtower` docs][watchtower-docs].
+    Images eligible for updates can configured with a [custom `command`][docker-docs-compose-command] that provides a list of container names, or via other supported options (eg: labels). This configuration is detailed in the [`watchtower` docs][watchtower-docs].
 
 !!! info "Manual cleanup"
 
     `watchtower` also supports running on-demand with `docker run` or `compose.yaml` via the `--run-once` option.
     
-    You can also directly invoke cleanup of Docker storage with:
+    You can alternatively invoke cleanup of Docker storage directly with:
 
     - [`docker image prune --all`][docker-docs-prune-image]
     - [`docker system prune --all`][docker-docs-prune-system] (_also removes unused containers, networks, build cache_).
-    - Avoid the `--all` option to only remove ["dangling" content][docker-prune-dangling] (_eg: Orphaned images_).
+
+    If you omit the `--all` option, this will instead only remove ["dangling" content][docker-prune-dangling] (_eg: Orphaned images_).
 
 [watchtower-dockerhub]: https://hub.docker.com/r/containrrr/watchtower
 [watchtower-cleanup]: https://containrrr.github.io/watchtower/arguments/#cleanup
 [watchtower-docs]: https://containrrr.dev/watchtower/
 
+[docker-docs-compose-command]: https://docs.docker.com/compose/compose-file/05-services/#command
 [docker-docs-prune-image]: https://docs.docker.com/engine/reference/commandline/image_prune/
 [docker-docs-prune-system]: https://docs.docker.com/engine/reference/commandline/system_prune/
 [docker-prune-dangling]: https://stackoverflow.com/questions/45142528/what-is-a-dangling-image-and-what-is-an-unused-image/60756668#60756668