Clarify installation error message that is shown when /nix/store exists but is not writable by the user
Clarify installation error message that is shown when /nix/store exists but is not writable by the user

dtzWill/nix,layus/nix,zimbatm/nix,bennofs/nix,NixOS/nix,dezgeg/nix,ehmry/nix,zimbatm/nix,rycee/nix,rycee/nix,vcunat/nix,ehmry/nix,vcunat/nix,ysangkok/nix,peti/nix,shlevy/nix,NixOS/nix,ehmry/nix,layus/nix,ysangkok/nix,peti/nix,dezgeg/nix,dtzWill/nix,pikajude/nix,dtzWill/nix,NixOS/nix,shlevy/nix,ehmry/nix,vcunat/nix,bennofs/nix,dezgeg/nix,dezgeg/nix,ehmry/nix,dezgeg/nix,layus/nix,zimbatm/nix,NixOS/nix,dtzWill/nix,wmertens/nix,wmertens/nix,ehmry/nix,bennofs/nix,ysangkok/nix,shlevy/nix,zimbatm/nix,pikajude/nix,peti/nix,wmertens/nix,wmertens/nix,peti/nix,bennofs/nix,layus/nix,shlevy/nix,vcunat/nix,dtzWill/nix,NixOS/nix,peti/nix,shlevy/nix,rycee/nix,layus/nix,rycee/nix,pikajude/nix,rycee/nix