Unhardcoding compaction_throughput_mb_per_sec variable

Change-Id: Ib0c23246741131444c2c96e9043aa6775ae11eda
diff --git a/README.rst b/README.rst
index 20b043f..dac41c7 100644
--- a/README.rst
+++ b/README.rst
@@ -136,6 +136,7 @@
         minimum_disk: 10
         name: 'Contrail'
         original_token: 0
+        compaction_throughput_mb_per_sec: 16
         data_dirs:
         - /var/lib/cassandra
         id: 1