docs: add missing documentation for --pull flag

These options were added in 22cd418967,
but did not update the documentation.

Signed-off-by: Chee Hau Lim <cheehau.lim@mobimeo.com>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

docs/reference/commandline/create.md

@@ -98,6 +98,7 @@ Options:
       --privileged                    Give extended privileges to this container
   -p, --publish value                 Publish a container's port(s) to the host (default [])
   -P, --publish-all                   Publish all exposed ports to random ports
+      --pull string                   Pull image before creating ("always"|"missing"|"never") (default "missing")
       --read-only                     Mount the container's root filesystem as read only
       --restart string                Restart policy to apply when a container exits (default "no")
                                       Possible values are: no, on-failure[:max-retry], always, unless-stopped