chore: Update comment to underscore free plans

[zachaysan]

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Changes

See this from @matthewelwell: #4054 (comment)

How did you test this code?

N/A

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[sentry-io]

🔍 Existing Issues For Review

Your pull request is modifying functions with the following pre-existing issues:

📄 File: api/organisations/views.py

Function	Unhandled Issue
get_queryset	TypeError: unsupported operand type(s) for +: 'relativedelta' and 'NoneType' /api/v1/organisations/{organisation... Event Count: 2

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.42%. Comparing base (848db5a) to head (9350f00).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4056   +/-   ##
=======================================
  Coverage   96.42%   96.42%           
=======================================
  Files        1148     1148           
  Lines       37430    37430           
=======================================
  Hits        36092    36092           
  Misses       1338     1338           

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