Add changelog note

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## [UNRELEASED]
 
 - Include the value of the `GITHUB_RUN_ATTEMPT` environment variable in the telemetry sent to GitHub. [#1640](https://github.com/github/codeql-action/pull/1640)
+- Improve the ease of debugging failed runs configured using [default setup](https://docs.github.com/en/code-security/code-scanning/automatically-scanning-your-code-for-vulnerabilities-and-errors/configuring-code-scanning-for-a-repository#configuring-code-scanning-automatically). The CodeQL Action will now upload diagnostic information to Code Scanning from failed runs configured using default setup. You can view this diagnostic information on the [tool status page](https://docs.github.com/en/code-security/code-scanning/automatically-scanning-your-code-for-vulnerabilities-and-errors/about-the-tool-status-page). [#1619](https://github.com/github/codeql-action/pull/1619)
 
 ## 2.2.11 - 06 Apr 2023