Fix Migration Guide link in README

[aggarw13]

Fix link for Migration Guide in README

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Codecov Report

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@@                  Coverage Diff                  @@
##             release-candidate     #1284   +/-   ##
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  Coverage                     ?   100.00%           
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  Files                        ?         5           
  Lines                        ?       317           
  Branches                     ?        73           
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  Hits                         ?       317           
  Misses                       ?         0           
  Partials                     ?         0           

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