Bumps nginx from 1.19.10 to 1.21.0. Signed-off-by: dependabot[bot] <support@github.com>
As @huiwang pointed out, using a custom network is unnecessary since the default bridge network works just as well.
Demonstrate that this pattern works. This is based on the example at <https://github.com/fatk/docker-letsencrypt-nginx-proxy-companion-examples/blob/master/docker-compose/v2/simple-site/docker-compose.yml>.