hint the minimum Ziti version

docs/guides/v0.4_metrics.md

@@ -0,0 +1,31 @@
+`v0.4` includes a new metrics infrastructure based on OpenZiti usage, which provides `zrok` with telemetry used to power end-user intelligence about shares, and also to power usage-based limits.
+
+# Configuration
+
+This requires a version of OpenZiti with a `fabric` dependency of `v0.22.52` or newer, which is satisfed by the `v0.27.6` release of OpenZiti Controller.
+
+## controller configuration
+
+```yaml
+network:
+  intervalAgeThreshold: 5s 
+  metricsReportInterval: 5s
+
+events:
+  jsonLogger:
+    subscriptions:
+      - type: fabric.usage
+        version: 3
+    handler:
+      type: file
+      format: json
+      path: /tmp/fabric-usage.log
+```
+
+## router configuration
+
+```yaml
+metrics:
+  reportInterval: 5s
+  intervalAgeThreshold: 5s
+```