Infoboxes for layers & extensions

This is a proposal for condensing the extension metadata into an [infobox](https://en.wikipedia.org/wiki/Infobox).

Motivation
Currently, the spec styles the registered layers and extensions in an odd way, having arguably less important information take up more space than necessary, all before the description/introduction of the extension. Typically, the description of the extension is more relevant than smaller bits, such as the stringified name, contact links, etc. Additionally, the amount of space wasted by the current design is unnecessary, and requires much scrolling (depending on device) to read the description of it.

Description
The implementation of this proposal will place these bits of information off to the right side, much like on MediaWikis, into a condensed and neat table. Most extension metadata will be moved here. The contributors section will be made into a collapsible list, or kept entirely from being hidden. The versioning requirements will be moved directly after the description.

An example from `VK_KHR_acceleration_structure` (before and after):

The order of these elements can be changed to make more sense (eg contact link at the bottom of the table).