Add updating weights example from ultralytics/yolov5

[xiguadong]

Resolve #114 and #92

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Codecov Report

Merging #117 (cef4a10) into master (f4f2e6a) will not change coverage.
The diff coverage is n/a.

❗ Current head cef4a10 differs from pull request most recent head 8ec4181. Consider uploading reports for the commit 8ec4181 to get more accurate results

@@           Coverage Diff           @@
##           master     #117   +/-   ##
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  Coverage   83.54%   83.54%           
=======================================
  Files           8        8           
  Lines         784      784           
=======================================
  Hits          655      655           
  Misses        129      129           

Flag	Coverage Δ
unittests	83.54% <ø> (ø)

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[zhiqwang]

LGTM, thanks for your contribution!

[zhiqwang]

西瓜东大佬 yyds!