webtunnel README doesn't have a "build the server" step
The WebTunnel README says to cp the server file to your bridge server, but doesn't say how to get or build the server file.
Shel suggested (in person) that you could get the server file from gitlab's CI, e.g. from https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/webtunnel/-/jobs/310087/artifacts/browse/build/amd64-linux/
But the more expected model is that people should either install a webtunnel package from their operating system, or build it themselves.
At the bottom of https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/webtunnel/-/blob/main/release/build.sh is the command line instruction for building webtunnel server-side:
go build -ldflags="-s -w" -o "build/$GOARCH-$GOOS/server" gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/webtunnel/main/server
So we should think about integrating that line into the README for people who aren't installing via docker or operating system package.