Remove dev env var requirement and update docs for latest config (#10483)

* Update docs for alerts and event review

* Add docs for camera groups

* Update reference config with new config values

* Remove env variable requirement

* Add to sidebar

* Update snapshot docs

* add zones example to detection docs too

* Generalize the zone docs

docs/docs/configuration/review.md

@@ -0,0 +1,47 @@
+---
+id: review
+title: Review
+---
+
+Review items are saved as periods of time where frigate detected events. After watching the preview of a review item it is marked as reviewed.
+
+## Restricting alerts to specific labels
+
+By default a review item will only be marked as an alert if a person or car is detected. This can be configured to include any object or audio label using the following config:
+
+```yaml
+# can be overridden at the camera level
+review:
+  alerts:
+    labels:
+      - car
+      - cat
+      - dog
+      - person
+      - speech
+```
+
+## Restricting detections to specific labels
+
+By default all detections that do not qualify as an alert qualify as a detection. However, detections can further be filtered to only include certain labels or certain zones.
+
+By default a review item will only be marked as an alert if a person or car is detected. This can be configured to include any object or audio label using the following config:
+
+```yaml
+# can be overridden at the camera level
+review:
+  detections:
+    labels:
+      - bark
+      - dog
+```
+
+## Restricting review items to specific zones
+
+By default a review item will be created if any `review -> alerts -> labels` and `review -> detections -> labels` are detected anywhere in the camera frame. You will likely want to configure review items to only be created when the object enters an area of interest, [see the zone docs for more information](./zones.md#restricting-alerts-and-detections-to-specific-zones)
+
+:::info
+
+Because zones don't apply to audio, audio labels will always be marked as an alert.
+
+:::