Elaborate on why we need to recycle CL segments when dropping tables

patch by Aleksandr Sorokoumov; reviewed by Caleb Rackliffe and Benjamin Lerer for CASSANDRA-16986

src/java/org/apache/cassandra/db/commitlog/CommitLogSegmentManager.java

@@ -291,7 +291,8 @@ public class CommitLogSegmentManager
      * Switch to a new segment, regardless of how much is left in the current one.
      *
      * Flushes any dirty CFs for this segment and any older segments, and then recycles
-     * the segments
+     * the segments. This is necessary to avoid resurrecting data during replay if a user
+     * creates a new table with the same name and ID. See CASSANDRA-16986 for more details.
      */
     void forceRecycleAll(Iterable<UUID> droppedCfs)
     {