Add amp-boilerplate to booleanHtmlAttributes #530
Description
According to the AMP specification, documents need to include a style tag with the boolean attribute amp-boilerplate in the <head> of the page. At the moment, adding amp-boilerplate: true to a style object in htmlAttrs outputs <style amp-boilerplate="true">, which leads to an AMP validation error. For this reason, amp-boilerplate should be added to the
booleanHtmlAttributes, as it has already been done for the attribute amp.