Add Coherence state store component docs - v1.16

[tmiddlet2666]

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Description

Added documentation for coherence state store. This PR replaces #4696, which was incorrectly done against v1.15. This has been rectified and changes suggested in last PR have been done.

Issue reference

dapr/components-contrib#3838

[tmiddlet2666]

@msfussell new PR to replace old one

[msfussell]

@tmiddlet2666 - Couple of light edits.

[msfussell]

@tmiddlet2666 - Really appreciate this amazing contribution!

[marcduiker]

@holopin-bot @tmiddlet2666 Here's a digital badge as a small token of appreciation.

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