docs(sample): Update parallel append sample to use StreamWriterV2

[yayi-google]

Thank you for opening a Pull Request! Before submitting your PR, there are a few things you can do to make sure it goes smoothly:

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Fixes #<issue_number_goes_here> ☕️

[lesv]

I don't see region tags anywhere and you appear to have added a example w/o a test.

• You should consider adding an IT test before committing.
• You should consider adding region tags before committing.

[codecov]

Codecov Report

Merging #883 (8a7da6d) into master (8e2ab01) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #883   +/-   ##
=========================================
  Coverage     80.85%   80.85%           
  Complexity     1014     1014           
=========================================
  Files            76       76           
  Lines          5500     5500           
  Branches        423      423           
=========================================
  Hits           4447     4447           
  Misses          880      880           
  Partials        173      173           

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[yayi-google]

I don't see region tags anywhere and you appear to have added a example w/o a test.

• You should consider adding an IT test before committing.
• You should consider adding region tags before committing.

We have IT test in the test fold.
We have region tags at the line 19.

[lesv]

Sg - that's why I gave a LGTM - I just have to ask. L19 wasn't shown in the PR