Add Coherence docs

[tmiddlet2666]

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Description

Introduce documentation for coherence state store.

Issue reference

https://github.com/dapr/components-contrib/pull/3838

[tmiddlet2666]

See https://github.com/dapr/docs/issues/4661

[tmiddlet2666]

@msfussell After moving to v1.16 there are a lot of commits, coming along with this, i'm going to close this and re-create against v1.16 properly.

[tmiddlet2666]

@msfussell please see new PR - https://github.com/dapr/docs/pull/4702