docs: rewrite README with structured overview and quick start guide

Replaces the minimal project description with a comprehensive README
including a component overview table, quick start instructions, common
Ansible operations, and links to detailed documentation. Aligns with
Red Panda Approval™ standards.

ansible/smtp4dev/docker-compose.yml.j2

@@ -0,0 +1,24 @@
+services:
+  smtp4dev:
+    image: rnwood/smtp4dev
+    pull_policy: always
+    container_name: smtp4dev
+    restart: unless-stopped
+    ports:
+      - "{{smtp4dev_port}}:80"
+      - "{{smtp4dev_smtp_port}}:25"
+      - "{{smtp4dev_imap_port}}:143"
+    volumes:
+      - smtp4dev_data:/smtp4dev
+    environment:
+      ServerOptions__BasePath: "/"
+      ServerOptions__Hostname: smtp4dev
+    logging:
+      driver: syslog
+      options:
+        syslog-address: "tcp://127.0.0.1:{{smtp4dev_syslog_port}}"
+        syslog-format: "{{syslog_format}}"
+        tag: "smtp4dev"
+
+volumes:
+  smtp4dev_data: