fix: use contraction to address Vale style check

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

Author: devin-ai-integration[bot]

fern/products/api-def/openapi-pages/extensions/examples.mdx

@@ -84,4 +84,4 @@ Fern supports syntax highlighting for the following languages in custom code sam
 - `swift`
 - `rust`
 
-If you specify a language that is not in this list, Fern will still display the code sample but without syntax highlighting.
+If you specify a language that's not in this list, Fern will still display the code sample but without syntax highlighting.