Update Copilot usage report docs for NDJSON downloads (#61488)

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Ben Ahmady <32935794+subatoi@users.noreply.github.com>

Author: 3 people

content/copilot/reference/copilot-usage-metrics/team-level-metrics.md

@@ -19,7 +19,7 @@ The same join recipe supports any team-level slice you need: per `(team, day)`,
 
 ## Fetching the reports
 
-The two reports referenced in this guide are downloaded in two steps. First, call the REST endpoint for the day you want. The endpoint returns time-limited signed URLs from which you can download the report files. Then download the JSON files those URLs point to. The user-team and per-user rows are in those JSON files; they are not returned inline by the REST endpoint.
+The two reports referenced in this guide are downloaded in two steps. First, call the REST endpoint for the day you want. The endpoint returns time-limited signed URLs from which you can download the report files. Then download the newline-delimited JSON (NDJSON) files those URLs point to. The user-teams and per-user rows are in those NDJSON files; they are not returned inline by the REST endpoint.
 
 | Report | Endpoint |
 |:--|:--|
@@ -33,7 +33,7 @@ Each endpoint returns a response of the form:
 ```json
 {
   "download_links": [
-    "https://example.com/copilot-user-teams-report-1.json"
+    "https://example.com/copilot-user-teams-report-1.ndjson"
   ],
   "report_day": "2026-05-07"
 }
@@ -89,7 +89,7 @@ The entity-level reports (`enterprise_28_day`, `organization_28_day`, `enterpris
 
 ## Example
 
-This minimal end-to-end example produces one day of organization-team metrics. The JSON shown below for each input report is a sample of the rows you would find in the file downloaded from one of that report's `download_links` (see [Fetching the reports](#fetching-the-reports) above).
+This minimal end-to-end example produces one day of organization-team metrics. The sample NDJSON rows below for each input report are like the rows you would find in the file downloaded from one of that report's `download_links` (see [Fetching the reports](#fetching-the-reports) above).
 
 Two users have {% data variables.product.prodname_copilot_short %} activity on 2026-05-07 in organization `999`:
 

content/copilot/tutorials/roll-out-at-scale/measure-success.md

@@ -100,7 +100,7 @@ Example response:
 ```json
 {
   "download_links": [
-    "https://example.com/copilot-usage-report.json"
+    "https://example.com/copilot-usage-report.ndjson"
   ],
   "report_start_day": "2025-07-18",
   "report_end_day": "2025-08-14"