Reword completion help to better indicate multiple projects can be specified at the same time

plugins/docker-project-manager/completions/_docker-project-manager

@@ -1,12 +1,12 @@
 #compdef docker-project-manager
 
 _docker_project_manager_comp() {
-  _arguments '--pull[Pull the project]' \
-    '*:projects:_files -W /docker -/' \
+  _arguments '--pull[Pull the project(s)]' \
+    '*:project(s):_files -W /docker -/' \
     + '(action)' \
-      '--up[Start the project]' \
-      '--down[Stop the project]' \
-      '--restart[Restart the project]'
+      '--up[Start the project(s)]' \
+      '--down[Stop the project(s)]' \
+      '--restart[Restart the project(s)]'
 }
 
 _docker_project_manager_comp "$@"