This package is a literal copy of the cmd/govulncheck/internal/govulncheck package in the vuln repo (https://go.googlesource.com/vuln).
The copy.sh does the copying, after removing all .go files here. To use it:
Clone the vuln repo to a directory next to the directory holding this repo (tools). After doing that your directory structure should look something like
~/repos/x/tools/gopls/... ~/repos/x/vuln/...
cd to this directory.
Run copy.sh.