Add nuimages gif

[xiliu8006]

add a nuimages demo in configs/nuimages/README.md

[codecov]

Codecov Report

Merging #268 (69ad6bc) into master (cfd6f99) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #268   +/-   ##
=======================================
  Coverage   49.89%   49.89%           
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  Files         172      172           
  Lines       11571    11571           
  Branches     1802     1802           
=======================================
  Hits         5773     5773           
  Misses       5424     5424           
  Partials      374      374           

Flag	Coverage Δ
unittests	49.89% <ø> (ø)

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[Tai-Wang]

Good demo, but is it convenient to use some brightly colored/colorful pictures :)

[xiliu8006]

Good demo, but is it convenient to use some brightly colored/colorful pictures :)

I am sorry, I only have the nuimages v1.0-mini dataset and it is the best one I found