MB-33332: Update SV CommittedState comment

Change-Id: I7be34bcbc7144d16746a3b4b2b414fb5521e05a1
Reviewed-on: http://review.couchbase.org/109991
Reviewed-by: Dave Rigby <[email protected]>
Tested-by: Build Bot <[email protected]>

Author: BenHuddleston

include/memcached/types.h

@@ -181,8 +181,8 @@ std::string to_string(DeleteSource deleteSource);
 /**
  * The committed state of the Item.
  *
- * Consists of four states: CommittedViaMutation, CommittedViaPrepare
- * Pending and PreparedMaybeVisible.
+ * Consists of six states: CommittedViaMutation, CommittedViaPrepare
+ * Pending, PreparedMaybeVisible, PrepareAborted, and PrepareCommitted.
  * The first two are generally considered as the same 'Committed' state
  * by external observers, but internally we need to differentiate between
  * them to write to disk / send over DCP hence having two different states.
@@ -192,6 +192,10 @@ std::string to_string(DeleteSource deleteSource);
  * Committed (but haven't yet been Committed locally) are marked as
  * PreparedMaybeVisible.
  *
+ * PrepareAborted and PrepareCommitted are used to identify prepares that exist
+ * in the HashTable after they have been completed which is required for
+ * Ephemeral.
+ *
  * Used in a bitfield in StoredValue hence explicit values for enums required.
  */
 enum class CommittedState : char {