Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

* Added an example of fronting the playbook's integrated Traefik reverse-proxy with the existing Caddy container (not the `apt-get` or `yum` installed Caddy).  Helpful for folks who have an existing server with a Caddy container already serving multiple applications.

* Update examples/reverse-proxies/caddy2-in-container/README.md

Co-authored-by: Slavi Pantaleev <slavi@devture.com>

* Update examples/reverse-proxies/caddy2-in-container/README.md

Co-authored-by: Slavi Pantaleev <slavi@devture.com>

* Update examples/reverse-proxies/caddy2-in-container/README.md

Co-authored-by: Slavi Pantaleev <slavi@devture.com>

* Code formatted, linted with yamllint

* README.md updated

* docs/configuring-playbook-own-webserver-caddy.md removed

---------

Co-authored-by: Slavi Pantaleev <slavi@devture.com>

* update http2 config due to deprecation

the previous way to let `http2` follow a `listen` was depracated, it
moved to `http2 on;`

* enable quic and http3

I hope the comments are somewhat understandable. if someone can describe
the `reuseport` part more concise, please do.

Updated the 'nginx reverse-proxy fronting' documentation with a guide for Nginx Proxy Manager, as you can't use the pre-existing nginx matrix.conf