add changelog for v2.1.0

Author: roseduan

CHANGELOG.md

@@ -1,3 +1,11 @@
+# Release 2.1.0 (2024-05-19)
+## 🚀 New Features
+* Feature: support iterator (https://github.com/lotusdblabs/lotusdb/pull/153) @akiozihao
+
+## 🎄 Enhancements
+* fix: Pass corresponding options to db.With... methods (https://github.com/lotusdblabs/lotusdb/pull/159) @akiozihao
+* feat(lint): add golangci-lint (https://github.com/lotusdblabs/lotusdb/pull/160) @akiozihao
+
 # Release 2.0.0 (2023-09-04)
 
 ## 🚀 New Features