docs: Adds required models field to variables documentation (#1709)

packages/web/src/content/docs/docs/config.mdx

@@ -317,6 +317,7 @@ Use `{env:VARIABLE_NAME}` to substitute environment variables:
   "model": "{env:OPENCODE_MODEL}",
   "provider": {
     "anthropic": {
+      "models": {},
       "options": {
         "apiKey": "{env:ANTHROPIC_API_KEY}"
       }