docs: added colorReplacements example

[elkmod]

Description

Added example for colorReplacements option in "Theme Colors Manipulation" section.

Linked Issues

#601

[netlify]

❌ Deploy Preview for shiki-next failed.

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🔨 Latest commit	6880b64
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[netlify]

❌ Deploy Preview for shiki-matsu failed.

Name	Link
🔨 Latest commit	6880b64
🔍 Latest deploy log	https://app.netlify.com/sites/shiki-matsu/deploys/65d8d63232add90007c62aab

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.17%. Comparing base (21d8187) to head (6880b64).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #602   +/-   ##
=======================================
  Coverage   96.17%   96.17%           
=======================================
  Files          70       70           
  Lines        5698     5698           
  Branches      751      751           
=======================================
  Hits         5480     5480           
  Misses        212      212           
  Partials        6        6           

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