update docs

Signed-off-by: Suleiman Dibirov <idsulik@gmail.com>

docs/reference/compose_watch.md

@@ -9,6 +9,7 @@ Watch build context for service and rebuild/refresh containers when files are up
 |:------------|:-----|:--------|:----------------------------------------------|
 | `--dry-run` |      |         | Execute command in dry run mode               |
 | `--no-up`   |      |         | Do not build & start services before watching |
+| `--prune`   |      |         | Prune dangling images on rebuild              |
 | `--quiet`   |      |         | hide build output                             |
 
 

docs/reference/docker_compose_watch.yaml

@@ -17,6 +17,16 @@ options:
       experimentalcli: false
       kubernetes: false
       swarm: false
+    - option: prune
+      value_type: bool
+      default_value: "false"
+      description: Prune dangling images on rebuild
+      deprecated: false
+      hidden: false
+      experimental: false
+      experimentalcli: false
+      kubernetes: false
+      swarm: false
     - option: quiet
       value_type: bool
       default_value: "false"