docs: add CHANGELOG for 2.6.1

Author: johzchen

CHANGELOG.md

@@ -19,6 +19,7 @@
 
 # Table of Contents
 
+- [2.6.1](#261)
 - [2.6.0](#260)
 - [2.5.0](#250)
 - [2.4.0](#240)
@@ -30,6 +31,16 @@
 - [1.5.0](#150)
 - [1.0.0](#100)
 
+# 2.6.1
+
+This release mainly contains bugfixes.
+
+`Manager API` 2.6.1 should be used with [Apache APISIX 2.5](https://apisix.apache.org/downloads/). It is not recommended to use with other Apache APISIX versions.
+
+### Bugfix
+- Fix: use remote address instead of client ip [#1831](https://github.com/apache/apisix-dashboard/pull/1831)
+- Fix: turn off online debug [#1903](https://github.com/apache/apisix-dashboard/pull/1903)
+
 # 2.6.0
 
 This release mainly improves UI and UE, bugfix and adds test cases.