[DOC] Link to quantile-forests in quantile regression examples

[adam2392]

Fixes #

Changes proposed in this pull request:

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (9792c85) 88.48% compared to head (e59ad4e) 88.48%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #220   +/-   ##
=======================================
  Coverage   88.48%   88.48%           
=======================================
  Files          54       54           
  Lines        4891     4891           
=======================================
  Hits         4328     4328           
  Misses        563      563           

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