Update README.md

Big-Data-Clusters/README.md

@@ -8,7 +8,5 @@ This folder contains notebooks related to troubleshooting common issues and task
 * **[CU4](https://github.com/microsoft/tigertoolbox/tree/master/Big-Data-Clusters/CU4/Public/content)**
 * **[CU5](https://github.com/microsoft/tigertoolbox/tree/master/Big-Data-Clusters/CU5/Public/content)**
 * **[CU6](https://github.com/microsoft/tigertoolbox/tree/master/Big-Data-Clusters/CU6/Public/content)**
-* **[CU8](https://github.com/microsoft/tigertoolbox/tree/master/Big-Data-Clusters/CU8/Public/content)**
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 **[hdfs-kerberos-tester.ipynb](https://github.com/microsoft/sql-server-samples/blob/master/samples/manage/hdfs-kerberos-tester/hdfs-kerberos-tester.ipynb)** - Notebook for troubleshooting HDFS Kerberos connections. More details about this toolset can be found [here](https://github.com/microsoft/sql-server-samples/tree/master/samples/manage/hdfs-kerberos-tester).