This is because it's referred to as ACKNOWLEDGEMENTS.md in the new css version output.
css
CounterStrikeSharp was created and is maintained by Michael "roflmuffin" Wilson.
Counter-Strike Sharp uses code borrowed from SourceMod, Source.Python, FiveM, Saul Rennison, source2gen and CS2Fixes.
See ACKNOWLEDGEMENTS.md for more information.
Current API Version: v199 (1.0.199+2b0923d)
This is because it's referred to as ACKNOWLEDGEMENTS.md in the new css version output.