Fix WriteBatch rep_ format for RangeDeletion records

Summary:
This is a small amount of general cleanup I made while experimenting with https://github.com/facebook/rocksdb/issues/3391.
Closes https://github.com/facebook/rocksdb/pull/3392

Differential Revision: D6788365

Pulled By: yiwu-arbug

fbshipit-source-id: 2716e5aabd5424a4dfdaa954361a62c8eb721ae2

db/write_batch.cc

@@ -15,10 +15,12 @@
 //    kTypeValue varstring varstring
 //    kTypeDeletion varstring
 //    kTypeSingleDeletion varstring
+//    kTypeRangeDeletion varstring varstring
 //    kTypeMerge varstring varstring
 //    kTypeColumnFamilyValue varint32 varstring varstring
-//    kTypeColumnFamilyDeletion varint32 varstring varstring
-//    kTypeColumnFamilySingleDeletion varint32 varstring varstring
+//    kTypeColumnFamilyDeletion varint32 varstring
+//    kTypeColumnFamilySingleDeletion varint32 varstring
+//    kTypeColumnFamilyRangeDeletion varint32 varstring varstring
 //    kTypeColumnFamilyMerge varint32 varstring varstring
 //    kTypeBeginPrepareXID varstring
 //    kTypeEndPrepareXID

include/rocksdb/db.h

@@ -979,7 +979,7 @@ class DB {
   // the file can fit in, and ingest the file into this level (2). A file that
   // have a key range that overlap with the memtable key range will require us
   // to Flush the memtable first before ingesting the file.
-  // In the second mode we will always ingest in the bottom mode level (see
+  // In the second mode we will always ingest in the bottom most level (see
   // docs to IngestExternalFileOptions::ingest_behind).
   //
   // (1) External SST files can be created using SstFileWriter

include/rocksdb/types.h

@@ -25,7 +25,7 @@ enum EntryType {
   kEntryOther,
 };
 
-// <user key, seqeence number and entry type> tuple.
+// <user key, sequence number, and entry type> tuple.
 struct FullKey {
   Slice user_key;
   SequenceNumber sequence;