docs: clarify Webhooks only preset limitations

Replaying deliveries that trigger tasks and creating webhook waiters
require additional task or waitpoint scopes beyond webhook access.

Co-authored-by: Eric Allam <534+ericallam@users.noreply.github.com>

Author: github-actions[bot]

docs/apikeys.mdx

@@ -83,7 +83,7 @@ Access presets define what a key can do. On the Free and Hobby plans only the **
 | **Task operator** | Trigger all or selected tasks and inspect or operate on their runs |
 | **Observer** | Read runs, tasks, batches, logs, traces, queues, errors, and webhooks |
 | **Operator** | Observe and operate on runs, queues, errors, and webhooks, and trigger tasks |
-| **Webhooks only** | Read and write [webhooks](/webhooks/overview), which are in private beta. No task or run access |
+| **Webhooks only** | Read and write [webhooks](/webhooks/overview), which are in private beta. Replaying deliveries that trigger tasks and creating webhook waiters require task or waitpoint scopes |
 | **Waitpoints only** | Create, list, and retrieve [waitpoint tokens](/wait-for-token). No task or run access |
 | **Deploy only** | Deploy versions, sync environment variables, and manage Preview branches |
 | **Variables only** | Read and write environment variables in this environment |