Add --help to subcommands in zsh completion

Signed-off-by: Steve Durrheimer <s.durrheimer@gmail.com>

contrib/completion/zsh/_docker-compose

@@ -162,6 +162,7 @@ __docker-compose_subcommand () {
     case "$words[1]" in
         (build)
             _arguments \
+                '--help[Print usage]' \
                 '--no-cache[Do not use cache when building the image]' \
                 '*:services:__docker-compose_services_from_build' && ret=0
             ;;
@@ -170,20 +171,24 @@ __docker-compose_subcommand () {
             ;;
         (kill)
             _arguments \
+                '--help[Print usage]' \
                 '-s[SIGNAL to send to the container. Default signal is SIGKILL.]:signal:_signals' \
                 '*:running services:__docker-compose_runningservices' && ret=0
             ;;
         (logs)
             _arguments \
+                '--help[Print usage]' \
                 '--no-color[Produce monochrome output.]' \
                 '*:services:__docker-compose_services_all' && ret=0
             ;;
         (migrate-to-labels)
-            _arguments \
+            _arguments -A '-*' \
+                '--help[Print usage]' \
                 '(-):Recreate containers to add labels' && ret=0
             ;;
         (port)
             _arguments \
+                '--help[Print usage]' \
                 '--protocol=-[tcp or udap (defaults to tcp)]:protocol:(tcp udp)' \
                 '--index=-[index of the container if there are mutiple instances of a service (defaults to 1)]:index: ' \
                 '1:running services:__docker-compose_runningservices' \
@@ -191,17 +196,20 @@ __docker-compose_subcommand () {
             ;;
         (ps)
             _arguments \
+                '--help[Print usage]' \
                 '-q[Only display IDs]' \
                 '*:services:__docker-compose_services_all' && ret=0
             ;;
         (pull)
             _arguments \
                 '--allow-insecure-ssl[Allow insecure connections to the docker registry]' \
+                '--help[Print usage]' \
                 '*:services:__docker-compose_services_from_image' && ret=0
             ;;
         (rm)
             _arguments \
                 '(-f --force)'{-f,--force}"[Don't ask to confirm removal]" \
+                '--help[Print usage]' \
                 '-v[Remove volumes associated with containers]' \
                 '*:stopped services:__docker-compose_stoppedservices' && ret=0
             ;;
@@ -211,6 +219,7 @@ __docker-compose_subcommand () {
                 '-d[Detached mode: Run container in the background, print new container name.]' \
                 '--entrypoint[Overwrite the entrypoint of the image.]:entry point: ' \
                 '*-e[KEY=VAL Set an environment variable (can be used multiple times)]:environment variable KEY=VAL: ' \
+                '--help[Print usage]' \
                 '(-u --user)'{-u,--user=-}'[Run as specified username or uid]:username or uid:_users' \
                 "--no-deps[Don't start linked services.]" \
                 '--rm[Remove container after run. Ignored in detached mode.]' \
@@ -221,13 +230,18 @@ __docker-compose_subcommand () {
                 '*::arguments: _normal' && ret=0
             ;;
         (scale)
-            _arguments '*:running services:__docker-compose_runningservices' && ret=0
+            _arguments \
+                '--help[Print usage]' \
+                '*:running services:__docker-compose_runningservices' && ret=0
             ;;
         (start)
-            _arguments '*:stopped services:__docker-compose_stoppedservices' && ret=0
+            _arguments \
+                '--help[Print usage]' \
+                '*:stopped services:__docker-compose_stoppedservices' && ret=0
             ;;
         (stop|restart)
             _arguments \
+                '--help[Print usage]' \
                 '(-t --timeout)'{-t,--timeout}"[Specify a shutdown timeout in seconds. (default: 10)]:seconds: " \
                 '*:running services:__docker-compose_runningservices' && ret=0
             ;;
@@ -235,6 +249,7 @@ __docker-compose_subcommand () {
             _arguments \
                 '--allow-insecure-ssl[Allow insecure connections to the docker registry]' \
                 '-d[Detached mode: Run containers in the background, print new container names.]' \
+                '--help[Print usage]' \
                 '--no-color[Produce monochrome output.]' \
                 "--no-deps[Don't start linked services.]" \
                 "--no-recreate[If containers already exist, don't recreate them.]" \
@@ -245,6 +260,7 @@ __docker-compose_subcommand () {
             ;;
         (version)
             _arguments \
+                '--help[Print usage]' \
                 "--short[Shows only Compose's version number.]" && ret=0
             ;;
         (*)