Merge pull request #17051 from thaJeztah/fix-volume-readonly-doc

remove incorrect "readonly" example

docs/userguide/dockervolumes.md

@@ -59,11 +59,6 @@ This will create a new volume inside a container at `/webapp`.
 > You can also use the `VOLUME` instruction in a `Dockerfile` to add one or
 > more new volumes to any container created from that image.
 
-Docker volumes default to mount in read-write mode, but you can also set it to be mounted read-only.
-
-    $ docker run -d -P --name web -v /opt/webapp:ro training/webapp python app.py
-
-
 ### Locating a volume
 
 You can locate the volume on the host by utilizing the 'docker inspect' command.