docs: add plaintext language to code block to prevent layout breaks

docs/migrations/migrating-to-v5.md

@@ -105,7 +105,7 @@ const action = useMainStore((state) => {
 
 The error message will be something like this:
 
-```
+```plaintext
 Uncaught Error: Maximum update depth exceeded. This can happen when a component repeatedly calls setState inside componentWillUpdate or componentDidUpdate. React limits the number of nested updates to prevent infinite loops.
 ```