nix run nixpkgs#silver-searcher -- -G '\.nix$' -0l 'description.*"[Aa]n?' pkgs \ | xargs -0 nix run nixpkgs#gnused -- -i '' -Ee 's/(description.*")[Aa]n? (.)/\1\U\2/'
To be checked in https://github.com/NixOS/nixpkgs/issues/81418