API design: Lookup hosts based on IdP email (#15305)

API changes for the following story:

- #13034

docs/REST API/rest-api.md

@@ -3036,9 +3036,11 @@ Request (`filters` is specified and empty, to delete all hosts):
 
 `Status: 200`
 
-### Get host's Google Chrome profiles
+### Get human-device mapping
 
-Retrieves a host's Google Chrome profile information which can be used to link a host to a specific user by email.
+Retrieves the end user's email(s) they use to log in to their Identity Provider (IdP) and Google Chrome profile.
+
+Note that IdP email is only supported on macOS hosts. It's collected once, during automatic enrollment (DEP), only if the end user authenticates with the IdP and the DEP profile has `await_device_configured` set to `true`.
 
 Requires [Fleetd](https://fleetdm.com/docs/using-fleet/fleetd), the osquery manager from Fleet. Fleetd can be built with [fleetctl](https://fleetdm.com/docs/using-fleet/adding-hosts#osquery-installer).
 
@@ -3062,6 +3064,10 @@ Requires [Fleetd](https://fleetdm.com/docs/using-fleet/fleetd), the osquery mana
 {
   "host_id": 1,
   "device_mapping": [
+    {
+      "email": "user@example.com",
+      "source": "identity_provider"
+    },
     {
       "email": "user@example.com",
       "source": "google_chrome_profiles"