modify ObjectReader._parserFactory comment (#5097)

Author: songsunkook

src/main/java/com/fasterxml/jackson/databind/ObjectReader.java

@@ -66,7 +66,7 @@ public class ObjectReader
     protected final DefaultDeserializationContext _context;
 
     /**
-     * Factory used for constructing {@link JsonGenerator}s
+     * Factory used for constructing {@link JsonParser}s
      */
     protected final JsonFactory _parserFactory;