history: fix required args for inspect attachment command

Signed-off-by: CrazyMax <[email protected]>

Author: crazy-max

commands/history/inspect_attachment.go

@@ -118,9 +118,9 @@ func attachmentCmd(dockerCli command.Cli, rootOpts RootOptions) *cobra.Command {
 	var options attachmentOptions
 
 	cmd := &cobra.Command{
-		Use:   "attachment [OPTIONS] REF [DIGEST]",
+		Use:   "attachment [OPTIONS] [REF [DIGEST]]",
 		Short: "Inspect a build record attachment",
-		Args:  cobra.RangeArgs(1, 2),
+		Args:  cobra.MaximumNArgs(2),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			if len(args) > 0 {
 				options.ref = args[0]

docs/reference/buildx_history_inspect_attachment.md

@@ -1,7 +1,7 @@
 # docker buildx history inspect attachment
 
 ```text
-docker buildx history inspect attachment [OPTIONS] REF [DIGEST]
+docker buildx history inspect attachment [OPTIONS] [REF [DIGEST]]
 ```
 
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