Fix erroneous space indentation of shell script

Signed-off-by: Morten Hekkvang <morten.hekkvang@sbab.se>
(cherry picked from commit fc19fb6d95)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

contrib/completion/bash/docker

@@ -561,7 +561,7 @@ __docker_services() {
 		shift
 	fi
 
-  __docker_q service ls --quiet --format "$format" "$@"
+	__docker_q service ls --quiet --format "$format" "$@"
 }
 
 # __docker_complete_services applies completion of services based on the current