docs: fix variable name from profileData to data in CSR page (ver…

…cel#34018)

Since the variable name is called `data`, I believe checking `profileData` will always be `undefined`.

## Documentation / Examples

- [x] Make sure the linting passes by running `yarn lint`

docs/basic-features/data-fetching/client-side.md

@@ -30,7 +30,7 @@ function Profile() {
   }, [])
 
   if (isLoading) return <p>Loading...</p>
-  if (!profileData) return <p>No profile data</p>
+  if (!data) return <p>No profile data</p>
 
   return (
     <div>