This fix is related to 27049 and 27047. For `--label` flag, if string slice is
used (like 27047), then quote can not be used in command and will result in
an error :
```
line 1, column 14: bare " in non-quoted-field
```
The issue 27047 has been fixed by 27049.
Recently I found out that both `docker network create --label` and `docker volume create --label`
still use string slice and will return the same error when quotes are used.
This fix fixes `docker network create --label` and `docker volume create --label`
by using `ListOpt` (as 27049) as well.
This fix has been tested and verified manually.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
Better formatting for usage template.
Group commands in usage to management/operation commands.
Remove the word Docker from the description of management commands.
Signed-off-by: Daniel Nephin <dnephin@docker.com>
