Document high availability cache

[russjones]

Problem

In #853, we introduced a cache that can be used to make Teleport more resilient in the face of failures. However, we don't have any documentation on how to enable or disable this and we also don't have any architectural diagrams that explain how this new HA concept works.

Proposed Solution

• In the Admin Guide, document how to use this new cache.
• In the Architecture documentation, document how this cache works.

[kontsevoy]

I am removing it from 2.3 milestone. IMO such documentation does not belong to product docs, because it does not affect how Teleport should be used. This is probably good for "contributor documentation" or maybe for a "Teleport under the hood" blog post.

Leaving it open though, this is good stuff we should be documenting, if not for users but for devs/contributors.

[russjones]

I was thinking it might be a good fit here: https://github.com/gravitational/teleport/blob/master/docs/2.0/architecture.md

[zmb3]

Closing this due to inactivity. Things have changed a lot since 2017 :-)