README: Fix typo in example code comment for ServeHTTP method (#193)

README.md

@@ -149,7 +149,7 @@ Define a router per host!
 // We just use a map here, in which we map host names (with port) to http.Handlers
 type HostSwitch map[string]http.Handler
 
-// Implement the ServerHTTP method on our new type
+// Implement the ServeHTTP method on our new type
 func (hs HostSwitch) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// Check if a http.Handler is registered for the given host.
 	// If yes, use it to handle the request.