install-darwin-multi-user: relax assumption check
install-darwin-multi-user: relax assumption check

The installer will error out if a user's shell configuration includes any mention of ~nix-profile~, even if this is in a comment. This change is designed to do the bare minimum to ignore lines beginning with a `#`.
pikajude/nix,vcunat/nix,shlevy/nix,dezgeg/nix,rycee/nix,peti/nix,ehmry/nix,peti/nix,layus/nix,dezgeg/nix,dezgeg/nix,zimbatm/nix,dtzWill/nix,rycee/nix,dezgeg/nix,ehmry/nix,peti/nix,zimbatm/nix,layus/nix,NixOS/nix,layus/nix,dtzWill/nix,NixOS/nix,ehmry/nix,zimbatm/nix,pikajude/nix,peti/nix,layus/nix,peti/nix,ehmry/nix,rycee/nix,ehmry/nix,dezgeg/nix,dtzWill/nix,ehmry/nix,shlevy/nix,layus/nix,zimbatm/nix,NixOS/nix,rycee/nix,dtzWill/nix,shlevy/nix,vcunat/nix,shlevy/nix,dtzWill/nix,vcunat/nix,shlevy/nix,rycee/nix,NixOS/nix,NixOS/nix,pikajude/nix,vcunat/nix