add changelog entry

Author: xeniape

CHANGELOG.md

@@ -7,6 +7,10 @@ All notable changes to this project will be documented in this file.
 ### Added
 
 - Helm: Allow Pod `priorityClassName` to be configured ([#840]).
+- Add end-of-support checker ([#852]).
+  - `EOS_CHECK_MODE` (`--eos-check-mode`) to set the EoS check mode. Currently, only "offline" is supported.
+  - `EOS_INTERVAL` (`--eos-interval`) to set the interval in which the operator checks if it is EoS.
+  - `EOS_DISABLED` (`--eos-disabled`) to disable the EoS checker completely.
 
 ### Fixed
 
@@ -18,6 +22,7 @@ All notable changes to this project will be documented in this file.
 
 [#840]: https://github.com/stackabletech/nifi-operator/pull/840
 [#844]: https://github.com/stackabletech/nifi-operator/pull/844
+[#852]: https://github.com/stackabletech/nifi-operator/pull/852
 
 ## [25.7.0] - 2025-07-23