SPARKC-244: Add TTL and WRITETIME documentation
SPARKC-244: Add TTL and WRITETIME documentation

shashwat7/spark-cassandra-connector,shashwat7/spark-cassandra-connector,debasish83/cassandra-driver-spark,ponkin/spark-cassandra-connector,viirya/spark-cassandra-connector,maasg/spark-cassandra-connector,datastax/spark-cassandra-connector,uncommoncode/spark-cassandra-connector,maasg/spark-cassandra-connector,christobill/spark-cassandra-connector,datastax/spark-cassandra-connector,christobill/spark-cassandra-connector,jimenefe/spark-cassandra-connector,jimenefe/spark-cassandra-connector,uncommoncode/spark-cassandra-connector,ponkin/spark-cassandra-connector,debasish83/cassandra-driver-spark,viirya/spark-cassandra-connector