Enhancement: fully support custom headers (#6125)

docs/configs/services.md

@@ -101,6 +101,25 @@ Each service can have multiple widgets attached to it, for example:
 
       Multiple widgets per service are not yet supported with Kubernetes ingress annotations.
 
+#### Custom HTTP headers
+
+Widgets that make HTTP calls support extra request headers via `headers`. This is useful when a reverse proxy expects a secret header.
+
+```yaml
+- UptimeRobot:
+    icon: uptimekuma.png
+    href: https://uptimerobot.com/
+    widget:
+      type: uptimerobot
+      url: https://api.uptimerobot.com
+      key: ${UPTIMEROBOT_API_KEY}
+      headers:
+        User-Agent: homepage
+        X-Auth-Key: your-secret-here
+```
+
+If you define services via Docker labels or Kubernetes annotations, use the same key with dot-notation (for example `homepage.widget.headers.X-Auth-Key=secret` or `gethomepage.dev/widget.headers.X-Auth-Key: "secret"`).
+
 #### Field Visibility
 
 Each widget can optionally provide a list of which fields should be visible via the `fields` widget property. If no fields are specified, then all fields will be displayed. The `fields` property must be a valid YAML array of strings. As an example, here is the entry for Sonarr showing only a couple of fields.