Miscellaneous fixes for nix-dev-shell#134102

Merged

bors merged 3 commits intorust-lang:masterfrom

WaffleLapkin:nix-dev-shell-fixups-2024-12-10

Dec 10, 2024

Commits on Dec 9, 2024

only ignore `{flake,default}.nix` and `{.envrc,.direnv/}` in the root
WaffleLapkin
committed
remove instructions to git exclude files in `src/nix-dev-shell/envrc-*`
WaffleLapkin
committed
provide `libz.so.1` in the `nix-dev-shell`
WaffleLapkin
committed