`SupervisedSqids` appears to not work as intended

[dcrck]

I followed the instructions in the intro documentation to add Sqids as a part of my supervision tree, but the example does not appear to work. Looking at the supervisor documentation, I can see why:

Finally, note it is also possible to simply pass the Counter module as a child:

children = [
  Counter
]

When only the module name is given, it is equivalent to {Counter, []}, which in our case would be invalid, which is why we always pass the initial counter explicitly.

So even if I pass SupervisedSqids as a child to my application supervisor, child_spec/0 will never be called.

I was only able to get my own options working when I copied the contents of __using__ into my module and removed use Sqids.