Add Unifi Controller service widget

Service-Widgets.md

@@ -464,6 +464,21 @@ widget:
 ```
 
 
+## Unifi Controller
+
+You can display general connectivity status from your Unifi (Network) Controller. When authenticating you will want to use an account that has at least read privileges.
+
+Allowed fields: `["uptime", "wan", "lan", "wlan"]`.
+
+```yaml
+widget:
+  type: unifi
+  url: https://unifi.host.or.ip:port
+  username: username
+  password: password
+```
+
+
 # System Utilities & Services
 
 System specific utilities and tools like message queues, databases, etc.