add readMe description

README.md

@@ -1,2 +1,20 @@
 # sugar
 sugar is a comprehensive, efficient, and reusable util function library of go
+
+
+## 💡 Usage
+
+You can import `sugar` using:
+
+```go
+import (
+    "github.com/phuhao00/sugar"
+)
+```
+
+Then use one of the helpers below:
+
+```go
+clamp := sugar.Clamp(2, 3, 5)
+fmt.Printf("clamp:%v", clamp)
+```

z_test.go

@@ -0,0 +1,11 @@
+package sugar
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestClamp(t *testing.T) {
+	clamp := Clamp(2, 3, 5)
+	fmt.Printf("clamp:%v", clamp)
+}