update changelog for 3.5.1 (#7657)

Author: randmonkey

CHANGELOG.md

@@ -7,6 +7,7 @@ Adding a new version? You'll need three changes:
 * Add the diff link, like "[2.7.0]: https://github.com/kong/kubernetes-ingress-controller/compare/v1.2.2...v1.2.3".
   This is all the way at the bottom. It's the thing we always forget.
 --->
+ - [3.5.1](#351)
  - [3.5.0](#350)
  - [3.4.7](#347)
  - [3.4.6](#346)
@@ -108,7 +109,9 @@ Adding a new version? You'll need three changes:
  - [0.0.5](#005)
  - [0.0.4 and prior](#004-and-prior)
 
-## Unreleased
+## [3.5.1]
+
+> Release date: 2025-07-31
 
 ### Fixed
 
@@ -4147,6 +4150,7 @@ Please read the changelog and test in your environment.
  - The initial versions  were rapildy iterated to deliver
    a working ingress controller.
 
+[3.5.1]: https://github.com/kong/kubernetes-ingress-controller/compare/v3.5.0...v3.5.1
 [3.5.0]: https://github.com/kong/kubernetes-ingress-controller/compare/v3.4.7...v3.5.0
 [3.4.7]: https://github.com/kong/kubernetes-ingress-controller/compare/v3.4.6...v3.4.7
 [3.4.6]: https://github.com/kong/kubernetes-ingress-controller/compare/v3.4.5...v3.4.6