feat: notification provider (#8)

Co-authored-by: Timo Behrendt <t.behrendt@t00n.de>
Co-committed-by: Timo Behrendt <t.behrendt@t00n.de>

README.md

@@ -23,6 +23,12 @@ dns_provider:
   config:
     api_key: <your-api-key>
     base_url: https://api.hosting.ionos.com/dns
+notification_provider:
+  type: gotify
+  config:
+    url: <your-gotify-host>
+    token: <your-token>
+    priority: 0
 domains:
   - tld: example.com
     subdomains:
@@ -52,4 +58,21 @@ url: <your-providers-URL>
 
 Examples for providers are:
 - https://ifconfig.me
-- https://api.ipify.org
+- https://api.ipify.org
+
+## Notification Providers
+The notification provider is used to send notifications whena IP address changes and a DNS record is updated.
+
+### Console
+The console notification provider is used to print the notification to the console. This is the default notification provider.
+
+### Gotify
+The Gotify notification provider is used to send notifications to a Gotify server.
+
+```yaml
+url: <your-gotify-host>
+token: <your-token>
+priority: 0
+```
+
+The priority must be between 0 and 4.