update change log

CHANGES.rst

@@ -1,6 +1,10 @@
 Changelog
 =========
 
+Notes:
+------
+- This python package specifies the version numbers only for directly imported python packages. This approach may result in a build failure of the package if there arise incompatibilities between imported packages over time. The build process of the master branch is regularely tested in an automatic process.
+
 2.5.1
 -----
 - Library upgrades (SQLAlchemy, shapely, geoalchemy2, responses, urllib3, lxml)
@@ -20,7 +24,7 @@ Changelog
 
 2.4.7
 -----
-- Add extract_index to disclaimer and general infomation (#1753)
+- Add extract_index to disclaimer and general infomation (#1753). Note that this improvement requires an additional attribute "extract_index" in tables "general_information" and "disclaimer" of the main schema.
 - Interlis bug fix (#1881)
 - Library upgrades (geoalchemy2, SQLAlchemy, jsonschema, lxml, responses, urllib3, pypdf)
 - Test coverage improvements