Cookbook: WebDAV

```bash

mkdir -p /tmp/webdav-root
cargo run -p webdav -- /tmp/webdav-root
# or: cargo run -p webdav -- 127.0.0.1:8080 /path/to/files

Env: WEBDAV_ROOT, WEBDAV_WRITE=1|true (default write on). Default listen 127.0.0.1:8080.