Add changelog entry

Author: mbg

CHANGELOG.md

@@ -4,7 +4,7 @@ See the [releases page](https://github.com/github/codeql-action/releases) for th
 
 ## [UNRELEASED]
 
-No user facing changes.
+- An error is now thrown if multiple inputs are provided for the GitHub-internal `analysis-kinds` input. The `analysis-kinds` input is experimental, for GitHub-internal use only, and may change without notice at any time. [#3892](https://github.com/github/codeql-action/pull/3892)
 
 ## 4.35.4 - 07 May 2026