docs: Updated docs to include usage of $bindable for bidirectional bindings and its possible riscs (#17121)

* docs: clarify usage of $bindable for bidirectional bindings and its possivle riscs

* Update documentation/docs/02-runes/06-$bindable.md

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Co-authored-by: Rich Harris <hello@rich-harris.dev>

documentation/docs/02-runes/06-$bindable.md

@@ -4,7 +4,7 @@ title: $bindable
 
 Ordinarily, props go one way, from parent to child. This makes it easy to understand how data flows around your app.
 
-In Svelte, component props can be _bound_, which means that data can also flow _up_ from child to parent. This isn't something you should do often, but it can simplify your code if used sparingly and carefully.
+In Svelte, component props can be _bound_, which means that data can also flow _up_ from child to parent. This isn't something you should do often — overuse can make your data flow unpredictable and your components harder to maintain — but it can simplify your code if used sparingly and carefully.
 
 It also means that a state proxy can be _mutated_ in the child.