docs: add custom registry information to faq (#799)

website/docs/faq.mdx

@@ -31,7 +31,7 @@ import CodeBlock from '@theme/CodeBlock';
 <details>
   <summary>How can I convert my own model for use with Tabby?</summary>
   <div>
-    <p>Follow the instructions provided in the <a href="https://github.com/TabbyML/tabby/blob/main/MODEL_SPEC.md">Model Spec</a>.</p>
-    <p>Please note that the spec is unstable and does not adhere to semver.</p>
+    <p>Since version 0.5.0, Tabby's inference now operates entirely on llama.cpp, allowing the use of any GGUF-compatible model format with Tabby. To enhance accessibility, we have curated models that we benchmarked, available at https://github.com/TabbyML/registry-tabby. Users are free to fork the repository to create their own registry. If a user's registry is located at https://github.com/USERNAME/registry-tabby, the model ID will be `--model USERNAME/model`.</p>
+    <p>For details on the registry format, please refer to https://github.com/TabbyML/registry-tabby/blob/main/models.json</p>
   </div>
 </details>