Update wrong usage workspace command description

Small update to the description to include available commands, rather than similar looking but wrong ones.

command/workspace_command.go

@@ -33,7 +33,7 @@ func (c *WorkspaceCommand) Help() string {
 	helpText := `
 Usage: terraform workspace
 
-  Create, list, change and delete Terraform workspaces.
+  New, list, select and delete Terraform workspaces.
 
 `
 	return strings.TrimSpace(helpText)