add favicon example (#1001)

examples/favicon/main.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"github.com/gin-gonic/gin"
+	"github.com/thinkerou/favicon"
+)
+
+func main() {
+	app := gin.Default()
+	app.Use(favicon.New("./favicon.ico"))
+	app.GET("/ping", func(c *gin.Context) {
+		c.String(200, "Hello favicon.")
+	})
+	app.Run(":8080")
+}