[Internals] Fix Profiler:find() arguments

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets | -

`Symfony\Component\HttpKernel\Profiler\Profiler::find()` signature does not allow for optional `$start` and `$end` arguments, only the Profiler storage classes do. I've added an additional example to clarify the last two arguments.