Update code examples in readme

[eungbean]

minor update on examples based on the current version of train.py.

• fix config to cfg
• [L870] add missing cfg

## What does this PR do?

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Fixes #\<issue_number>

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## Did you have fun?

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[codecov-commenter]

Codecov Report

Base: 83.71% // Head: 83.71% // No change to project coverage 👍

Coverage data is based on head (627fe82) compared to base (37b57ce).
Patch has no changes to coverable lines.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #494   +/-   ##
=======================================
  Coverage   83.71%   83.71%           
=======================================
  Files           9        9           
  Lines         350      350           
=======================================
  Hits          293      293           
  Misses         57       57           

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[ashleve]

Thank you for the update!