prune: fix build cache prune warning

Signed-off-by: David Karlsson <35727626+dvdksn@users.noreply.github.com>

cli/command/system/prune.go

@@ -125,7 +125,7 @@ func confirmationMessage(dockerCli command.Cli, options pruneOptions) string {
 		if options.all {
 			warnings = append(warnings, "all build cache")
 		} else {
-			warnings = append(warnings, "all dangling build cache")
+			warnings = append(warnings, "unused build cache")
 		}
 	}
 

cli/command/system/prune_test.go

@@ -36,7 +36,7 @@ func TestPrunePromptFilters(t *testing.T) {
   - all stopped containers
   - all networks not used by at least one container
   - all dangling images
-  - all dangling build cache
+  - unused build cache
 
   Items to be pruned will be filtered with:
   - label!=foo=bar

docs/reference/commandline/system_prune.md

@@ -29,7 +29,7 @@ WARNING! This will remove:
         - all stopped containers
         - all networks not used by at least one container
         - all dangling images
-        - all build cache
+        - unused build cache
 Are you sure you want to continue? [y/N] y
 
 Deleted Containers: