docs: add v3 migration doc

[TerryHowe]

No description provided.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.54%. Comparing base (0324380) to head (65f66b5).

Additional details and impacted files

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  Coverage   82.54%   82.54%           
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  Files          64       64           
  Lines        4779     4779           
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  Hits         3945     3945           
- Misses        510      511    +1     
+ Partials      324      323    -1     

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[shizhMSFT]

I think it is too early for this doc. At least, we should have an v3 alpha version first.

[TerryHowe]

Well, if we have it, we can iterate on it rather than try to figure it out after the fact.

[sabre1041]

This is a good start. While we are still in initial design/development mode, it would be good to note that the migration path is still under development explicitly in this document

Also, is this document to be linked/referenced from another document?

[TerryHowe]

I updated the document to note it is a work in progress.

I was hoping to that each breaking change PR would make a note in this document.

When this release is done, it would be moved to the document site.

[TerryHowe]

I've changed this so it creates a directory so we won't need to deal with merge conflicts. Each breaking change can have a short document and at the end we'll take them all add them to the docs site.