remove =false from options that default to false in the docs

This re-aligns the docs with what the cmd line now does.

Signed-off-by: Doug Davis <dug@us.ibm.com>

docs/reference/commandline/pull.md

@@ -14,9 +14,9 @@ parent = "smn_cli"
 
     Pull an image or a repository from the registry
 
-      -a, --all-tags=false          Download all tagged images in the repository
+      -a, --all-tags                Download all tagged images in the repository
       --disable-content-trust=true  Skip image verification
-      --help=false                  Print usage
+      --help                        Print usage
 
 Most of your images will be created on top of a base image from the
 [Docker Hub](https://hub.docker.com) registry.