[CI] Update Foundry Upgrades plugin docs (#1156)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

docs/modules/ROOT/pages/foundry/pages/foundry-defender.adoc

@@ -34,6 +34,8 @@ DEFENDER_KEY=<Your API key>
 DEFENDER_SECRET=<Your API secret>
 ----
 
+NOTE: The API key for the above must at least have the capability to Manage Deployments (optionally Manage Relayers is needed to create an approval process with a Relayer). You can configure your API keys at https://defender.openzeppelin.com/#/settings/api-keys.
+
 == Network Selection
 
 The network that is used with OpenZeppelin Defender is determined by the network that Foundry is connected to.