Fix pluralisation on response from installing mods

main.go

@@ -44,13 +44,23 @@ var commands = []Command{
 				}
 			}()
 
-			for _, archivePath := range providedArguments[1:] {
+			var archivePaths = providedArguments[1:]
+
+			if len(archivePaths) > 1 {
+				for _, archivePath := range archivePaths {
 					if installError := game.InstallMod(archivePath); installError != nil {
 						return "", installError
 					}
 				}
 
 				return "mods installed", nil
+			}
+
+			if installError := game.InstallMod(archivePaths[0]); installError != nil {
+				return "", installError
+			}
+
+			return "mod installed", nil
 		},
 	},