Update comments about default WALRecoveryMode

Summary:
The default changed in 6a14f7a976 but this comment was not updated.
Closes https://github.com/facebook/rocksdb/pull/3409

Differential Revision: D6808264

Pulled By: maysamyabandeh

fbshipit-source-id: 0d7e2a054eb181e9a144fcb783cf0b2c77219bc0

include/rocksdb/options.h

@@ -274,14 +274,14 @@ struct ColumnFamilyOptions : public AdvancedColumnFamilyOptions {
 enum class WALRecoveryMode : char {
   // Original levelDB recovery
   // We tolerate incomplete record in trailing data on all logs
-  // Use case : This is legacy behavior (default)
+  // Use case : This is legacy behavior
   kTolerateCorruptedTailRecords = 0x00,
   // Recover from clean shutdown
   // We don't expect to find any corruption in the WAL
   // Use case : This is ideal for unit tests and rare applications that
   // can require high consistency guarantee
   kAbsoluteConsistency = 0x01,
-  // Recover to point-in-time consistency
+  // Recover to point-in-time consistency (default)
   // We stop the WAL playback on discovering WAL inconsistency
   // Use case : Ideal for systems that have disk controller cache like
   // hard disk, SSD without super capacitor that store related data