Fixing internal links for Snippets & Examples

Author: mzitnik

README.md

@@ -8,8 +8,8 @@ Table of Contents
 * [Supported Flink Versions](#supported-flink-versions)
 * [Installation](#installation)
 * [DataStream API](#dataStream-api)
-    * [Snippets](#snippets)
-    * [Examples](#examples)
+    * [Snippets](#snippet)
+    * [Examples](#example)
 * [Table API](#table-api)
     * [Artifacts](#artifacts-1)
     * [Examples](#examples-1)