Update docs for docker create to include --rm flag

Since 20848 has been merged and both `docker create` and
`docker run` share the same `runconfig` parser, now both
`docker run` and `docker create` allow to specify the
`--rm` flag. However, docs for `docker create` has not
been udpated yet.

This fix updates docs for `docker create` so that `--rm`
flag has been included.

This fix is related to 20848 and 25577.

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

docs/reference/commandline/create.md

@@ -90,6 +90,7 @@ Options:
       --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
+      --rm                          Automatically remove the container when it exits
       --runtime string              Runtime to use for this container
       --security-opt value          Security Options (default [])
       --shm-size string             Size of /dev/shm, default value is 64MB.