Note down some cache-busting scenarios

[stevenjmesser]

What

Brainstorm and draft a few scenarios when we will want to invalidate the cache, so that users can access fresh or the latest data. Think about how long we might want caches to last before they're automatically invalidated or refreshed.

Why

We want users to have the latest data at all times, however we also need to implement caching to make our system more performant. This requires us to balance users' needs with our system's needs.

Acceptance criteria

• We have at least 2 scenarios in which we'd invalidate caches
• In-app memory will be cleared as well as caches
• We know how long the caches should last before being automatically refreshed
• We have initial ideas on how to do it, based on documentation (for Cloudfront, for example)