Updated the doc to correct that Cody-gateway users can also use Claude model and how site admins can enable it (#1188)

Updated the doc to correct that Cody-gateway users can also use Claude
model and how site admins can enable it

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Author: rakeshjosh2003

docs/cody/capabilities/supported-models.mdx

@@ -65,4 +65,12 @@ Cody uses a set of models for autocomplete which are suited for the low latency
 | :----------- | :------------- | :------- | :------ | :------------- | --- | --- | --- | --- | --- | --- |
 | Fireworks.ai | Qwen 2.5 Coder | ✅        | ✅       | ✅              |     |     |     |     |     |     |
 
-<Callout type="note">Enterprise users not using Cody Gateway get a Claude Sonnet-based model for Smart Apply.</Callout>
+Fireworks.ai is the default model for cody-gateway, but if you wish to switch to Claude models, Site admins can do it following these steps-
+
+<Callout type="note">Go to "Site admin"</Callout>
+
+<Callout type="note">Click on the "Feature flags"</Callout>
+
+<Callout type="note">Search for cody-smart-apply-instant-mode-enabled feature flag</Callout>
+
+<Callout type="note">Turn off/delete the "cody-smart-apply-instant-mode-enabled" feature flag</Callout>