feat: support Let's Encrypt tls.

examples/auto-tls/main.go

@@ -0,0 +1,17 @@
+package main
+
+import (
+	"github.com/gin-gonic/gin"
+)
+
+func main() {
+	r := gin.Default()
+
+	// Ping handler
+	r.GET("/ping", func(c *gin.Context) {
+		c.String(200, "pong")
+	})
+
+	// Listen and Server in 0.0.0.0:443
+	r.RunAutoTLS(":443", "/var/www/.cache", "example.com")
+}