Add IceVision docs page

[ethanwharris]

What does this PR do?

Fixes # (issue)

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• Did you write any new necessary tests? [not needed for typos/docs]
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[tchaton]

Love It !

[tchaton]

Don't merge this PR :)

[codecov]

Codecov Report

Merging #677 (ae79be2) into master (a154e51) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #677   +/-   ##
=======================================
  Coverage   90.20%   90.20%           
=======================================
  Files         192      192           
  Lines        9905     9905           
=======================================
  Hits         8935     8935           
  Misses        970      970           

Flag	Coverage Δ
unittests	90.20% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
flash/core/integrations/icevision/transforms.py	69.44% <100.00%> (ø)

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