add migration guide info to php8.1 changelog (#123)

diff --git a/core/php8.1Action/CHANGELOG.md b/core/php8.1Action/CHANGELOG.md
index 7bec0b5..86530ee 100644
--- a/core/php8.1Action/CHANGELOG.md
+++ b/core/php8.1Action/CHANGELOG.md
@@ -17,6 +17,9 @@
 #
 -->
 
+## Migrating from PHP 7 to PHP 8
+PHP 8 as new features and some incompatiblities. See [migration guide](https://www.php.net/manual/en/migration80.php) for more information.
+
 ## Next Release
 Initial release