Update documentation for ODIS 2.0.0 (CIP-40)

[nategraf]

Including

• Signer operations + internal runbook
• README(s)
• Internal Design Docs
• External facing docs
• Code structure UML diagrams for dependency injection and inheritance structures

Note: this will exclude any documentation on how to use the Identity SDK to interact with ODIS, as that could change as we update the SDK for ASv2

Will not include