docs: convert examples to be functional components

[layershifter]

[github-actions[bot]]

size-limit report

Path	Size
bundle-size/dist/Button.size.js	54.01 KB (0%)
bundle-size/dist/Icon.size.js	27.33 KB (0%)
bundle-size/dist/Image.size.js	49.58 KB (0%)
bundle-size/dist/Modal.size.js	62.54 KB (0%)
bundle-size/dist/Portal.size.js	37.18 KB (0%)

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (5646905) 99.50% compared to head (6b54e0b) 99.50%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4453   +/-   ##
=======================================
  Coverage   99.50%   99.50%           
=======================================
  Files         186      186           
  Lines        3466     3466           
=======================================
  Hits         3449     3449           
  Misses         17       17           

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