Added a note to update the website after a stable release

docs/release_checklist.md

@@ -16,6 +16,8 @@ mechanical work.
 
 * Do the release
 
+* Update the website file include/header.inc.php to reflect the new version
+
 ## New bugfix release
 
 * Check that no new API/ABI was added
@@ -28,6 +30,8 @@ mechanical work.
 
 * Do the release
 
+* Update the website file include/header.inc.php to reflect the new version
+
 ## After a feature release
 
 * Create a branch like `release-2.24.x`