Update API2.md

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: cfm

API2.md

@@ -286,7 +286,7 @@ Broadly speaking, each event will terminate in one of the following states:
     idempotence is not enforced for error states.
 
 4.  **Overload:** If a client submits more than
-    `securedrop.journalist_app.api2.MAX_EVENTS` events, the server will skip
+    `securedrop.journalist_app.api2.EVENTS_MAX` events, the server will skip
     processing them, and the client will receive HTTP `429 Too Many Requests`
     for the entire `BatchRequest`.