Added PHPDocs to allow autocompletion in IDE

[bretto36]

Hi There. Thanks for this package, we've just started using it. I saw it was missing PHPDoc blocks for the properties on the model. I like to let me IDE do as much thinking for me as possible.

We had a scenario where our project needed to report on how many people logged in on each day for 3 months and doing $log-> didn't show any values in my IDE. So thought i'd do a PR.

$user->authentications()
        ->where('login_at', '>', Carbon::now()->subMonthsNoOverflow(3))
        ->get()
        ->countBy(function(AuthenticationLog $log) {
            return $log->login_at->timezone(Tenancy::getTenant()->timezone)->format('Ymd');
        });