docs(samples): add samples for write/rejoin/purge user events

[tetiana-karasova]

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Fixes #<issue_number_goes_here> 🦕

[snippet-bot]

Here is the summary of changes.

You are about to add 3 region tags.

• samples/interactive-tutorials/events/purge_user_event.py:16, tag retail_purge_user_event
• samples/interactive-tutorials/events/rejoin_user_event.py:16, tag retail_rejoin_user_event
• samples/interactive-tutorials/events/write_user_event.py:16, tag retail_write_user_event

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