add mkdocs

docs/widgets/services/caddy.md

@@ -0,0 +1,12 @@
+---
+title: Caddy
+description: Caddy Widget Configuration
+---
+
+Allowed fields: `["upstreams", "requests", "requests_failed"]`.
+
+```yaml
+widget:
+    type: caddy
+    url: http://caddy.host.or.ip:adminport # default admin port is 2019
+```