fix(docs): update max body size for usage service (#6757)

Author: dotansimha

packages/web/docs/src/content/specs/usage-reports.mdx

@@ -11,7 +11,7 @@ import usageReportV2Schema from '../../../../../services/usage/usage-report-v2.s
 The official JavaScript Hive Client (`@graphql-hive/core`) collects executed operations and sends
 them in batches (as a single report, when a buffer is full or every few seconds) over HTTP.
 
-> It's recommended to send a report for more than 1 operation. The maximum payload size is 1 MB.
+> It's recommended to send a report for more than 1 operation. The maximum payload size is 15 MB.
 
 | Name                 | Value                                                                                                                      |
 | -------------------- | -------------------------------------------------------------------------------------------------------------------------- |