Fix `WriteBatchBase::DeleteRange` API comment (#4935)

Summary:
The `DeleteRange` end key is exclusive, not inclusive. Updated API comment accordingly.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4935

Differential Revision: D13905406

Pulled By: ajkr

fbshipit-source-id: f577db841a279427991ecf9005cd56b30c8eb3c7

include/rocksdb/write_batch_base.h

@@ -69,7 +69,7 @@ class WriteBatchBase {
                               const SliceParts& key);
   virtual Status SingleDelete(const SliceParts& key);
 
-  // If the database contains mappings in the range ["begin_key", "end_key"],
+  // If the database contains mappings in the range ["begin_key", "end_key"),
   // erase them. Else do nothing.
   virtual Status DeleteRange(ColumnFamilyHandle* column_family,
                              const Slice& begin_key, const Slice& end_key) = 0;