docs(react): add a missing closing curly brace on a reactivity example (#1248)

Author: yjoer

docs/framework/react/guides/reactivity.md

@@ -34,7 +34,7 @@ The `form.Subscribe` component is best suited when you need to react to somethin
 <form.Subscribe
   selector={(state) => state.values.firstName}
   children={(firstName) => (
-    <form.Field>{(field) => <input name="lastName" value={field.state.lastName} onChange={field.handleChange}/></form.Field>
+    <form.Field>{(field) => <input name="lastName" value={field.state.lastName} onChange={field.handleChange}/>}</form.Field>
   )}
 />
 ```