Fix md generation for kubectl docs

Display usage string, not long help, as code, remove angle brackets from
output (.md interprets as tags and hides).

pkg/kubectl/cmd/delete.go

@@ -58,7 +58,7 @@ $ kubectl delete pods --all`
 func (f *Factory) NewCmdDelete(out io.Writer) *cobra.Command {
 	var filenames util.StringList
 	cmd := &cobra.Command{
-		Use:     "delete (-f filename | <resource> (<id> | -l <label> | --all))",
+		Use:     "delete ([-f FILENAME] | (RESOURCE [(ID | -l label | --all)]",
 		Short:   "Delete a resource by filename, stdin, or resource and ID.",
 		Long:    delete_long,
 		Example: delete_example,