Add new caddy image (#7574)

* Add new caddy image
* Update to v2.0.0-rc.3

Signed-off-by: Dave Henderson <[email protected]>

library/caddy

@@ -0,0 +1,16 @@
+# this file is generated with gomplate:
+# template: https://github.com/caddyserver/caddy-docker/blob/0097550f86a7ac7cb95042149d4d62ca415750a3/stackbrew.tmpl
+# config context: https://github.com/caddyserver/caddy-docker/blob/82359bcbcd3d43b8703605afc60370b6c5f87d1f/stackbrew-config.yaml
+Maintainers: Dave Henderson (@hairyhenderson)
+
+Tags: 2.0.0-rc.3, 2.0.0-rc.3-alpine, alpine, latest
+GitRepo: https://github.com/caddyserver/caddy-docker.git
+Directory: alpine
+GitCommit: 82359bcbcd3d43b8703605afc60370b6c5f87d1f
+Architectures: amd64
+
+Tags: 2.0.0-rc.3-builder, builder
+GitRepo: https://github.com/caddyserver/caddy-docker.git
+Directory: builder
+GitCommit: 82359bcbcd3d43b8703605afc60370b6c5f87d1f
+Architectures: amd64