Add docs on run_from fields

heartbeat/docs/heartbeat-observer-options.asciidoc

@@ -1,7 +1,27 @@
 [[configuration-observer-options]]
 == Add observer and geo metadata
 
-It is often useful to view and query various attributes of the instance Heartbeat is running on. This data is attached to events via the <<add-observer-metadata,`add_observer_metadata`>> processor. This processor populates the ECS `observer.*` fields. One field of particular utility is the `observer.geo.name` field, which you can configure via this processor. Use this field to create distinctive geographic regions for your uptime checks. You might label your regions by datacenter name or geographic region, e.g. `virginia-dc-1`, or `us-east-1a`, or `virginia-us`.
+Use the `heartbeat.run_from` option to set the geographic location fields relevant to a given heartbeat instance.
 
-Note that Heartbeat should not be used with the similarly named <<add-host-metadata,`add_host_metadata`>> processor. In ECS parlance the host is the thing that is monitored, not the thing doing the monitoring, which is the observer.
+The `run_from` option is used to label the geographic location where the monitor is running.
+Note, you can also set the `run_from` option on an individual monitor to apply a unique setting to just that monitor.
 
+The `run_from` option takes two top-level fields:
+
+* `id`: A string used to uniquely identify the geographic location. It is indexed as the `observer.name` field.
+* `geo`: A map conforming to https://www.elastic.co/guide/en/ecs/current/ecs-geo.html[ECS geo fields]. It is indexed under `observer.geo`.
+
+Example:
+
+```yaml
+heartbeat.run_from:
+  id: my-custom-geo
+  geo:
+	name: nyc-dc1-rack2
+	location: 40.7128, -74.0060
+	continent_name: North America
+	country_iso_code: US
+	region_name: New York
+	region_iso_code: NY
+	city_name: New York
+```

heartbeat/docs/monitors/monitor-common-options.asciidoc

@@ -105,6 +105,47 @@ If the timeout is exceeded, {beatname_uc} publishes a `service-down` event. If t
 value specified for `timeout` is greater than `schedule`, intermediate checks
 will not be executed by the scheduler.
 
+[float]
+[[monitor-run-from]]
+=== `run_from`
+
+Use the `run_from` option to set the geographic location fields relevant to a given heartbeat monitor.
+
+The `run_from` option is used to label the geographic location where the monitor is running.
+Note, you can also set the `run_from` option on all monitors via the `heartbeat.run_from` option.
+
+The `run_from` option takes two top-level fields:
+
+* `id`: A string used to uniquely identify the geographic location. It is indexed as the `observer.name` field.
+* `geo`: A map conforming to https://www.elastic.co/guide/en/ecs/current/ecs-geo.html[ECS geo fields]. It is indexed under `observer.geo`.
+
+Example:
+
+```yaml
+- type: http
+  # Set enabled to true (or delete the following line) to enable this example monitor
+  enabled: true
+  # ID used to uniquely identify this monitor in elasticsearch even if the config changes
+  id: geo-test
+  # Human readable display name for this service in Uptime UI and elsewhere
+  name: Geo Test
+  # List or urls to query
+  urls: ["http://example.net"]
+  # Configure task schedule
+  schedule: '@every 10s'
+  run_from:
+    id: my-custom-geo
+    geo:
+      name: nyc-dc1-rack1
+      location: 40.7128, -74.0060
+      continent_name: North America
+      country_iso_code: US
+      region_name: New York
+      region_iso_code: NY
+      city_name: New York
+
+```
+
 [float]
 [[monitor-fields]]
 ==== `fields`