fixed invalid image url

website/index.html

@@ -10,7 +10,7 @@
 	<meta property="og:title" content="GoCQL">
 	<meta property="og:type" content="website">
 	<meta property="og:url" content="http://tux21b.org/gocql/">
-	<meta property="og:image" content="http://tux21b.org/gocql/logo.png">
+	<meta property="og:image" content="http://tux21b.org/gocql/gocql.png">
 	<meta property="og:description" content="GoCQL - Modern Cassandra client for the Go">
 	<style>
 	body { border-top: 4px solid #666; }