Add changelog note

Author: henrymercer

CHANGELOG.md

@@ -4,7 +4,7 @@ See the [releases page](https://github.com/github/codeql-action/releases) for th
 
 ## [UNRELEASED]
 
-No user facing changes.
+- Fix incorrect minimum required Git version for [improved incremental analysis](https://github.com/github/roadmap/issues/1158): it should have been 2.36.0, not 2.11.0. [#3781](https://github.com/github/codeql-action/pull/3781)
 
 ## 4.35.0 - 27 Mar 2026