docs(intersection): add upstream feature explanation

[soblin]

Description

update document

Tests performed

Not applicable.

Effects on system behavior

Not applicable.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (c9e6dda) 14.99% compared to head (b0ea676) 15.00%.
Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6426   +/-   ##
=======================================
  Coverage   14.99%   15.00%           
=======================================
  Files        1838     1838           
  Lines      127099   127074   -25     
  Branches    38075    38065   -10     
=======================================
  Hits        19062    19062           
+ Misses      86715    86690   -25     
  Partials    21322    21322           

Flag	Coverage Δ		*Carryforward flag
differential	4.51% <ø> (?)
total	15.00% <ø> (+<0.01%)	⬆️	Carriedforward from c9e6dda

*This pull request uses carry forward flags. Click here to find out more.

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