docs: standardize readme format

readme.md

@@ -1,14 +1,34 @@
-# Overview
+# Ansible Role: Unbound
 
-This role configures an Unbound DNS server.
+Install and configure [Unbound](https://nlnetlabs.nl/projects/unbound/) DNS server.
 
-## Supported Operating Systems
+## Variables
 
-| Operating System | Version |
-| --- | ----- |
-| Alpine | 3.23 |
-| Debian | 13 |
+| Variable | Required | Default | Description |
+|----------|----------|---------|-------------|
+| `unbound_upstream_dns` | No | `["8.8.8.8", "1.1.1.1"]` | Upstream DNS servers |
+| `unbound_allow_access` | Yes | `[]` | Networks allowed to query DNS |
+| `unbound_zones` | Yes | `[]` | DNS zones to configure |
 
-## Tags
+## Example
 
-This role has no tags.
+```yaml
+unbound_upstream_dns:
+  - "1.1.1.1"
+  - "8.8.8.8"
+
+unbound_allow_access:
+  - name: "internal-lan"
+    network: "10.0.0.0/8"
+  - name: "dmz"
+    network: "192.168.1.0/24"
+
+unbound_zones:
+  - zone: "internal.example.com"
+    type: "static"
+    records:
+      - name: "server1.internal.example.com"
+        value: "10.0.1.10"
+      - name: "server2.internal.example.com"
+        value: "10.0.1.11"
+```