[Docs] Align Note with the Output Naming Convention

[JiangJiaWei1103]

Why are the changes needed?

To better align the note in the tasks page with the actual naming convention of output variables.

What changes were proposed in this pull request?

Change the default name of output variables from outx to ox, where x is an ordinal number starting from 0.

Related Doc Section

https://docs.flyte.org/en/latest/user_guide/basics/named_outputs.html

Check all the applicable boxes

• I updated the documentation accordingly.
• All commits are signed-off.

Docs link

https://flyte--5919.org.readthedocs.build/en/5919/user_guide/basics/tasks.html

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 36.84%. Comparing base (13b3d82) to head (d18c3c7).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #5919   +/-   ##
=======================================
  Coverage   36.84%   36.84%           
=======================================
  Files        1309     1309           
  Lines      130967   130967           
=======================================
+ Hits        48252    48253    +1     
+ Misses      78531    78530    -1     
  Partials     4184     4184           

Flag	Coverage Δ
unittests-datacatalog	51.58% <ø> (ø)
unittests-flyteadmin	54.12% <ø> (ø)
unittests-flytecopilot	11.73% <ø> (ø)
unittests-flytectl	62.40% <ø> (ø)
unittests-flyteidl	6.92% <ø> (ø)
unittests-flyteplugins	53.64% <ø> (ø)
unittests-flytepropeller	43.00% <ø> (ø)
unittests-flytestdlib	55.41% <ø> (+0.01%)	⬆️

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