更新 'README.md'

README.md

@@ -505,4 +505,4 @@ for (int level = 0; level <= max_level_with_files; level++) {
     TEST_CompactRange(level, begin, end);
   }
 ```
-
+Related Pr : [avoid lose efficacy for CompactRange by demiaowu · Pull Request #502 · google/leveldb](https://github.com/google/leveldb/pull/502)