✅ Add a couple testable examples

generators_examples_test.go

@@ -0,0 +1,20 @@
+package nomino
+
+import "fmt"
+
+func ExampleWithGenerator_custom_generator() {
+	gen := func() (string, error) {
+		return "hello", nil
+	}
+	option := WithGenerator(gen)
+
+	str, _ := Make(NewConfig(option))
+	fmt.Println(str)
+
+	str, _ = Make(NewConfig(option, WithoutExtension()))
+	fmt.Println(str)
+
+	// Output:
+	// hello.txt
+	// hello
+}