Add Vaults system-level documentation to docs.inter.trade

[otoole-brendan]

What is the Problem Being Solved?

As part of Vaults launch - we need to provide various user documentation and make available on doc.inter.trade (via Gitbook).

The scope of this issue is vaults system level documentation i.e. how vaults, liquidation, auction and oracle network operate.

Description of the Design

Collateral already exists to inform this documentation - just needs to be formatted accordingly for docs.inter.trade consumption

Security Considerations

N/A

Test Plan

QA of docs.inter.trade

[otoole-brendan]

Completed by @rowgraus last week. See docs.inter.trade