public function update(CourseRequest $request, $id)
{
$course = Course::findOrFail($id);
$course->fill($request->only(['name']));
$course->save();
$course->users()->sync($request->input('users'));
$course->teachers()->sync($request->input('teachers'));
session()->flash('success', 'Los datos del curso se han actualizado.');
return redirect()->back();
}
