repo: Rename compose templates to compose.yaml.jinja

It is a short, concicse name for the compose (and one of the ways that
docker officially recommends to name the files), and jinja is the
careful recommendation of the jinja docs.

https://jinja.palletsprojects.com/en/stable/templates/#template-file-extension

roles/caddy/templates/docker-compose.yaml.j2

@@ -1,21 +0,0 @@
-services:
-  caddy:
-    image: lucaslorentz/caddy-docker-proxy:ci-alpine
-    ports:
-      - 80:80
-      - 443:443
-    networks:
-      - caddy
-    volumes:
-      - /var/run/docker.sock:/var/run/docker.sock
-      - caddy_data:/caddy
-    labels:
-      caddy.auto_https: "off"
-
-networks:
-  caddy:
-    external: true
-
-volumes:
-  caddy_data: {}
-