update license

src/torchmetrics/functional/text/chrf.py

@@ -15,7 +15,9 @@
 # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 # Copyright 2017 Maja Popovic
-# Licensed under the Apache License, Version 2.0 (the "License")
+# The code is derived from https://github.com/m-popovic/chrF/blob/6d3c384/chrF%2B%2B.py
+# The original author and copyright holder have agreed to relicense the derived code  under the Apache License, Version 2.0 (the "License")
+# Reference to the approval: https://github.com/Lightning-AI/torchmetrics/pull/2701#issuecomment-2316891785
 
 from collections import defaultdict
 from itertools import chain