[WIP] docs: add raise user error section

[machichima]

Tracking issue

#6083

Why are the changes needed?

Error handling method is unclear for raw container.

What changes were proposed in this pull request?

Add a short description of how to trigger flyte user error and enable retries in raw containers example.

How was this patch tested?

Setup process

Screenshots

Check all the applicable boxes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

Related PRs

Docs link

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 37.10%. Comparing base (ba331fd) to head (6160273).
Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6084   +/-   ##
=======================================
  Coverage   37.10%   37.10%           
=======================================
  Files        1318     1318           
  Lines      132331   132331           
=======================================
+ Hits        49097    49099    +2     
+ Misses      78961    78960    -1     
+ Partials     4273     4272    -1     

Flag	Coverage Δ
unittests-datacatalog	51.58% <ø> (ø)
unittests-flyteadmin	54.10% <ø> (ø)
unittests-flytecopilot	30.99% <ø> (ø)
unittests-flytectl	62.29% <ø> (ø)
unittests-flyteidl	7.23% <ø> (ø)
unittests-flyteplugins	53.82% <ø> (ø)
unittests-flytepropeller	42.63% <ø> (ø)
unittests-flytestdlib	57.57% <ø> (+0.03%)	⬆️

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[pingsutw]

thank you!