Swagger: Add information to API Token header (#7585)

* Add a description to the API Token header for swagger

routers/api/v1/api.go

@@ -43,6 +43,7 @@
 //          type: apiKey
 //          name: Authorization
 //          in: header
+//          description: API tokens must be prepended with "token" followed by a space.
 //     SudoParam:
 //          type: apiKey
 //          name: sudo