doc: optimize readme

README.md

@@ -13,5 +13,32 @@
 ## Usage
 
 ```go
-tlsConn = terasu.Use(tlsConn)
+cli := http.Client{
+    Transport: &http.Transport{
+        DialTLS: func(network, addr string) (net.Conn, error) {
+            host, port, err := net.SplitHostPort(addr)
+			if err != nil {
+				return nil, err
+			}
+            addrs, err := net.DefaultResolver.LookupHost(ctx, host)
+            if err != nil {
+                return nil, err
+            }
+            conn, err := net.Dial(network, net.JoinHostPort(addrs[0], port))
+            if err != nil {
+                return nil, err
+            }
+            tlsConn := tls.Client(conn, &tls.Config{
+                ServerName: host,
+            })
+            err = terasu.Use(tlsConn).Handshake()
+            if err != nil {
+                _ = tlsConn.Close()
+                return nil, err
+            }
+            return tlsConn, nil
+        },
+    },
+}
+resp, err := cli.Get(url)
 ```