Need a --force flag in Example 3 update-image-set-metadata.rst

[laiqmuhh]

During testing for customer-facing metrics, found a gap in current documentation for instance removal from imageset Ref in example 3. The correct command needs --force flag

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.38%. Comparing base (c4681b5) to head (de2f7b2).
⚠️ Report is 80 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #10006      +/-   ##
===========================================
- Coverage    93.39%   93.38%   -0.01%     
===========================================
  Files          210      210              
  Lines        17052    17055       +3     
===========================================
+ Hits         15925    15927       +2     
- Misses        1127     1128       +1     

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