Merge pull request #2912 from albers/completion-run--pull

Add bash completion for `docker run|create --pull`

contrib/completion/bash/docker

@@ -1955,6 +1955,7 @@ _docker_container_run_and_create() {
 		--pid
 		--pids-limit
 		--publish -p
+		--pull
 		--restart
 		--runtime
 		--security-opt
@@ -2153,6 +2154,10 @@ _docker_container_run_and_create() {
 			esac
 			return
 			;;
+		--pull)
+		  COMPREPLY=( $( compgen -W 'always missing never' -- "$cur" ) )
+		  return
+		  ;;
 		--runtime)
 			__docker_complete_runtimes
 			return