Update inaccurate example to 'of' replacement. (#6939)

The arguments to 'of' should not be an array. When running the stackblitz, the output is:
[1, 2, 3]
1
2
3

That is the 'of' emitting the array, and the scheduled emitting each item in the array separately; not the same thing.

docs_app/content/deprecations/scheduler-argument.md

@@ -37,7 +37,7 @@ Following code example demonstrate this process.
 import { of, asyncScheduler, scheduled } from 'rxjs';
 
 // Deprecated approach
-of([1, 2, 3], asyncScheduler).subscribe((x) => console.log(x));
+of(1, 2, 3, asyncScheduler).subscribe((x) => console.log(x));
 // suggested approach
 scheduled([1, 2, 3], asyncScheduler).subscribe((x) => console.log(x));
 ```