nix-instantiate: Allow --dry-run as a synonym for --readonly-mode
nix-instantiate: Allow --dry-run as a synonym for --readonly-mode

--dry-run is more consistent with nix-env and nix-store.

ttuegel/nix,bjornfor/nix,vizanto/nix,dtzWill/nix,garbas/nix,bjornfor/nix,nbp/nix,rycee/nix,dtzWill/nix,bennofs/nix,rycee/nix,nbp/nix,bennofs/nix,tchajed/nix,rycee/nix,NixOS/nix,puffnfresh/nix,jcumming/nix,dtzWill/nix,garbas/nix,acowley/nix,gridaphobe/nix,dezgeg/nix,jcumming/nix,bennofs/nix,dtzWill/nix,NixOS/nix,layus/nix,gebner/nix,zimbatm/nix,rowhit/nix,jcumming/nix,zimbatm/nix,puffnfresh/nix,ysangkok/nix,pikajude/nix,shlevy/nix,ttuegel/nix,acowley/nix,acowley/nix,wmertens/nix,gebner/nix,joelmo/nix,rycee/nix,offlinehacker/nix,zimbatm/nix,shlevy/nix,tchajed/nix,dezgeg/nix,ehmry/nix,vizanto/nix,ehmry/nix,vizanto/nix,puffnfresh/nix,ehmry/nix,bjornfor/nix,vcunat/nix,rowhit/nix,layus/nix,peti/nix,zimbatm/nix,vcunat/nix,ttuegel/nix,tchajed/nix,garbas/nix,aucampia/nix,wmertens/nix,rycee/nix,offlinehacker/nix,peti/nix,layus/nix,nbp/nix,dtzWill/nix,ttuegel/nix,ehmry/nix,ehmry/nix,gridaphobe/nix,layus/nix,offlinehacker/nix,vcunat/nix,NixOS/nix,rowhit/nix,joelmo/nix,ehmry/nix,dezgeg/nix,NixOS/nix,ysangkok/nix,puffnfresh/nix,ysangkok/nix,wmertens/nix,garbas/nix,gebner/nix,nbp/nix,offlinehacker/nix,peti/nix,NixOS/nix,wmertens/nix,rowhit/nix,tchajed/nix,aucampia/nix,shlevy/nix,layus/nix,aucampia/nix,vcunat/nix,peti/nix,jcumming/nix,pikajude/nix,aucampia/nix,joelmo/nix,vizanto/nix,dezgeg/nix,peti/nix,gebner/nix,gridaphobe/nix,shlevy/nix,bennofs/nix,dezgeg/nix,gridaphobe/nix,joelmo/nix,pikajude/nix,garbas/nix,acowley/nix,bjornfor/nix,shlevy/nix