Improve SimplePagination doc

[glebfox]

1. Add autoLoad attribute description - Sets whether items count should be loaded automatically. When the autoload is disabled the component doesn't know the total count of items and shows a button with [?]. When it's enabled the component makes a query to get the total count of items and shows it. The default value is false.

2. Add css, ariaLabel, ariaLabelBy common attributes