docs: show extended values through the component reference

[VividLemon]

Clear and concise description of the problem

In situations where components extend the values of other components, there needs to be an extension to the component reference.

I believe something like (BAvatar example)

BAvatar props
badge	default: false	badge desc
Omit<BLinkProps, 'event' | 'routerTag'>
variant	'secondary' (Not a BLink default)	(desc taken automatically from BLink)
active	undefined -- (default taken from BLink)	(desc taken automatically from BLink)

The purpose is to make this automatic. Without requiring you to re-declare props all over the place.

[VividLemon]

related: #1580 (comment)