Update actor state store docs to include strong consistency requirement

[jjcollinge]

Signed-off-by: Jonathan Collinge [email protected]

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Description

Updates the state store documentation for actor state stores to make it clear that it must be setup with strong consistency as outlined in the state store design reference https://github.com/dapr/dapr/blob/master/docs/decision_records/api/API-005-state-store-behavior.md. Its possible that people are using state stores that are "actor compatible" but with a weaker consistency model which can cause undefined behaviour.

Issue reference

[msfussell]

LGTM

[jjcollinge]

@yaron2 shall I close this or ok to merge?

[yaron2]

Technically we don't require the state store to be strongly consistent, meaning Dapr will not error or issue a warning if a non consistent store is chose. That's because the runtime code doesn't make explicit use of the consistency settings when using the State API interface from contrib. That said it should be recommended that users choosing a multi-replica database set it to strong consistency from the database side, so I'm happy if the PR is changed to reflect that