Fixed an missing '-' on the "--rm"

Docker-DCO-1.1-Signed-off-by: William Henry <whenry@redhat.com> (github: ipbabble)

 Changes to be committed:
	modified:   contrib/man/md/docker-build.md

contrib/man/md/docker-build.md

@@ -6,7 +6,7 @@ docker-build - Build a container image from a Dockerfile source at PATH
 
 # SYNOPSIS
 **docker build** [**--no-cache**[=*false*] [**-q**|**--quiet**[=*false*]
- [**-rm**] [**-t**|**--tag**=*tag*] PATH | URL | -
+ [**--rm**] [**-t**|**--tag**=*tag*] PATH | URL | -
 
 # DESCRIPTION
 This will read the Dockerfile from the directory specified in **PATH**.