Update release checklist.

Author: baagaard-usgs

release-notes/checklist.txt

@@ -13,7 +13,7 @@ TESTING
 SOURCE CODE
 
   * Reserve DOI on Zenodo and update version and DOI in code.
-  * Update citation information (year) in preface.md.
+  * Update citation information (year) in preface.md and PyLithApp.py.
   * Add changes to CHANGES.
     * List contributors https://github.com/geodynamics/pylith/graphs/contributors?from=2024-01-01&to=2024-06-05&type=c
   * Add release notes in release-notes.