Fix Nix file order docs

[infinisil]

shell.nix file is used first if it exists, see

nix-direnv/direnvrc

Lines 340 to 344 in 9178f71

	if [[ -e "shell.nix" ]]; then
	nixfile="./shell.nix"
	elif [[ -e "default.nix" ]]; then
	nixfile="./default.nix"
	fi

[infinisil]

Though ideally it would also use default.nix if it exists, a lot of shell.nix's just defer to default.nix

[Mic92]

Thanks!

[Mic92]

Though ideally it would also use default.nix if it exists, a lot of shell.nix's just defer to default.nix

We need to stay compatible with use nix from the direnv stdlib instead. So this is not an option.

[infinisil]

Ah, I guess yeah the default file to load should stay the same, but I think both files should be watched for changes by default.

[infinisil]

Opened #409 to track this further