Add or Update Packages
First, you need to find the package you are looking for.
Visit nix-package-search
Search for a package, e.g. go-. The first time you search, it may be
slow and take almost a minute to get results, but it will be faster
after that.
When you see the version of the package you want, click on the eye icon to unfold the settings.
Add or update the package to nix/default.nix