Add info about cakephp/cakephp#17886

Author: ADmad

en/appendices/5-1-migration-guide.rst

@@ -149,6 +149,9 @@ ORM
 - Setting the ``preserveKeys`` option on association finder queries. This can be
   used with ``formatResults()`` to replace association finder results with an
   associative array.
+- The ORM can now map SQLite columns with name containing ``json`` to ``JsonType``.
+  This currently an opt-in feature which can be enabled by setting the ``ORM.mapJsonTypeForSqlite``
+  configure value to ``true`` in your app's bootstrap.
 
 TestSuite
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