[Documentation] Update aside/badge for Assets page

[RobTobias123]

Outcome

When a new icon or illustration asset has been added to the system, it is reflected in the lists on the Docs Assets page and is brought to attention using the 'updated' badge and/or the aside on the page content in the same way updates are mentioned to components pages.

Value

Clear communication and awareness that a change or addition has been made to the assets available to the consumer, encourages use of the new where appropriate and increases the diversity of the ns-icon/ns-illustration components.

Scope

• Discover how to add a badge to a 'non-component' page
  • Does this affect the format of badge.json

Process

• Add 'Updated' badge to the Assets link in LHS nav
• Add 'Aside' to the Assets page in the relevant section
  • E.g.: Underneath the 'Icons' or 'Illustrations' heading

[evecrabb]

Looking at this work I think it would be more future-thinking to include Tokens in this scope as well, considering that's something that gets updated - albeit not very often, does (i.e. the red link colour).

[evecrabb]

PR

• Feat/773 badge expansion and doc improvements #810

I'm fully aware that I've gone slightly outside of scope by adding tokens support. Apologies in advance but it felt like a good thing to add.

[RobTobias123]

Reviewed and approved