Document the setup a bit, so I don't have to reverse-engineer
it (again) later.

Make svn.xiph.org available agail by proxying traffic to
a container running the server:

    docker build -t svn .
    docker run --rm -d \
      --name svn \
      -v /var/svn/xiph:/var/svn \
      -p 127.0.0.1:7376:80 \
      svn

Then terminate tls connections in the host webserver and proxy
requests to localhost:7376.