fix: update Suomi.fi IDP test/production metadata

This is a dummy README.md change commit to trigger Kesäseteli's backend
release. The original code changes is actually in commit
5b7aab6

refs YJDH-711

backend/kesaseteli/kesaseteli/settings.py

@@ -433,6 +433,7 @@
 else:
     SUOMIFI_SERVICE_NAME_EXTRA = env("SUOMIFI_SERVICE_NAME_EXTRA")
 
+# See backend/shared/README.md for info about the Suomi.fi IDP metadata files
 SUOMIFI_IDP_METADATA_FILENAME = (
     "idp-metadata-secondary.xml"
     if SUOMIFI_TEST