Update 5.x-patch.md

doc/5.x-patch.md

@@ -59,6 +59,7 @@ git push origin 5.X
 
 * Check open PRs for `5.X`: https://github.com/civicrm/civicrm-core/pulls
 * Check release notes: https://github.com/civicrm/civicrm-core/blob/5.X/release-notes.md
+* If this is an ESR patch, check `distmaker/patchset-baselines.txt` to ensure it specifies the last public version.
 * In Jenkins, review the scheduled tests for `5.X` and determine if anything should block the release.
     * https://test.civicrm.org/job/CiviCRM-Core-Matrix/
     * https://test.civicrm.org/job/CiviCRM-Ext-Matrix/