docs(flaky-tests): document monitor category sections in UI

flaky-tests/detection/index.mdx

@@ -28,6 +28,13 @@
 
 ## Monitor Types
 
+Trunk groups monitors into two categories based on what they do when they activate:
+
+- **Health classification monitors** determine a test's overall health status (healthy, flaky, or broken). When one activates, the test's status changes across the dashboard, CI annotations, and notifications.
+- **Lifecycle and performance monitors** apply labels to tests based on lifecycle events or performance characteristics. They do not affect health status. These monitors appear in a separate section of the monitors page.
+
+### Health Classification Monitors
+
 | Monitor | What it detects | Available actions | Plan availability | Default state |
 |---|---|---|---|---|
 | [**Pass-on-Retry**](./pass-on-retry-monitor) | A test fails then passes on the same commit (retry after failure) | Classify (flaky) or [apply labels](../management/test-labels#automatic-labeling-from-monitors) | Team and above | Enabled |
@@ -81,7 +88,7 @@
 
 While muted, the monitor is excluded from the test's status calculation. If the muted monitor was the only active classifying monitor, the test transitions from flaky to healthy for the duration of the mute. When the mute expires, the monitor is automatically included in the next status evaluation. If it's still active, the test will be flagged again.
 
 You can also unmute a monitor early from the test case view.
 
 {/* SCREENSHOT: Mute button and duration picker on the test case monitor list.
 Show the test case detail page with a monitor's mute button visible,