Add stop signal to the docs.

Signed-off-by: Daniel Nephin <dnephin@docker.com>

docs/compose-file.md

@@ -469,9 +469,17 @@ port (a random host port will be chosen).
 
 Override the default labeling scheme for each container.
 
-      security_opt:
-        - label:user:USER
-        - label:role:ROLE
+    security_opt:
+      - label:user:USER
+      - label:role:ROLE
+
+### stop_signal
+
+Sets an alternative signal to stop the container. By default `stop` uses
+SIGTERM. Setting an alternative signal using `stop_signal` will cause
+`stop` to send that signal instead.
+
+    stop_signal: SIGUSR1
 
 ### ulimits
 
@@ -479,11 +487,11 @@ Override the default ulimits for a container. You can either specify a single
 limit as an integer or soft/hard limits as a mapping.
 
 
-      ulimits:
-        nproc: 65535
-        nofile:
-          soft: 20000
-          hard: 40000
+    ulimits:
+      nproc: 65535
+      nofile:
+        soft: 20000
+        hard: 40000
 
 ### volumes, volume\_driver
 
@@ -564,7 +572,7 @@ subcommand documentation for more information.
 Specify which volume driver should be used for this volume. Defaults to
 `local`. An exception will be raised if the driver is not available.
 
-      driver: foobar
+     driver: foobar
 
 ### driver_opts
 
@@ -572,9 +580,9 @@ Specify a list of options as key-value pairs to pass to the driver for this
 volume. Those options are driver dependent - consult the driver's
 documentation for more information. Optional.
 
-      driver_opts:
-        foo: "bar"
-        baz: 1
+     driver_opts:
+       foo: "bar"
+       baz: 1
 
 
 ## Variable substitution

docs/index.md

@@ -45,8 +45,7 @@ A `docker-compose.yml` looks like this:
       redis:
         image: redis
     volumes:
-      logvolume01:
-        driver: default
+      logvolume01: {}
 
 For more information about the Compose file, see the
 [Compose file reference](compose-file.md)