docs: add sdk-variables to navigation sidebar

Co-Authored-By: [email protected] <[email protected]>

Author: devin-ai-integration[bot]

fern/products/api-def/api-def.yml

@@ -58,6 +58,8 @@ navigation:
           - page: SDK method names
             path: ./openapi-pages/extensions/method-names.mdx
             slug: method-names
+          - page: SDK variables
+            path: ./openapi-pages/extensions/sdk-variables.mdx
           - page: Tag display names
             path: ./openapi-pages/extensions/tag-display-name.mdx
           - page: Parameter names