service update: fix service create example

Service create expects the name to be passed using the
`--name` flag, not as a positional parameter

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 0cd7c6aa0288e8219ba21ac24a92a09ab73d91e1)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Upstream-commit: 0cfe29431c348d92323f176b702b199709f18a45
Component: cli

Author: thaJeztah

components/cli/docs/reference/commandline/service_update.md

@@ -158,16 +158,13 @@ service name.
 ```bash
 $ docker service create \
     --name=myservice \
-    --mount \
-      type=volume,source=test-data,target=/somewhere \
-    nginx:alpine \
-    myservice
+    --mount type=volume,source=test-data,target=/somewhere \
+    nginx:alpine
 
 myservice
 
 $ docker service update \
-    --mount-add \
-      type=volume,source=other-volume,target=/somewhere-else \
+    --mount-add type=volume,source=other-volume,target=/somewhere-else \
     myservice
 
 myservice