fix typo (#6099)

Summary:
fix a typo in struct ReadOptions
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6099

Differential Revision: D18729618

fbshipit-source-id: 850a9df71f7c0abebea17feab77b8d5874e8ba0a

include/rocksdb/options.h

@@ -1181,7 +1181,7 @@ struct ReadOptions {
   // "iterate_upper_bound" defines the extent upto which the forward iterator
   // can returns entries. Once the bound is reached, Valid() will be false.
   // "iterate_upper_bound" is exclusive ie the bound value is
-  // not a valid entry.  If iterator_extractor is not null, the Seek target
+  // not a valid entry. If prefix_extractor is not null, the Seek target
   // and iterate_upper_bound need to have the same prefix.
   // This is because ordering is not guaranteed outside of prefix domain.
   //

java/src/main/java/org/rocksdb/ReadOptions.java

@@ -476,7 +476,7 @@ public class ReadOptions extends RocksObject {
    *
    * The upper bound is exclusive i.e. the bound value is not a valid entry.
    *
-   * If iterator_extractor is not null, the Seek target and iterate_upper_bound
+   * If prefix_extractor is not null, the Seek target and iterate_upper_bound
    * need to have the same prefix. This is because ordering is not guaranteed
    * outside of prefix domain.
    *