docs: mention data source for SQLite DB (is not XML) (#541)

* docs: mention data source for SQLite DB (is not XML)

* Update src/server/data/README.md

Co-authored-by: kevin <[email protected]>

---------

Co-authored-by: kevin <[email protected]>

Author: hf-kklein

src/server/data/README.md

@@ -1,6 +1,7 @@
 # AHB.db
 
 The ahb.db file is the sqlite database file that contains the AHB data.
+It was populated using the machine-readable Anwendungshandbuecher, scraped by kohlrahbi from `.docx` files.
 
 It is created by the ahb.sql file in the database/sql folder.
 You can find the way how to create the database [here](https://github.com/Hochfrequenz/machine-readable_anwendungshandbuecher/issues/336).