[DOP-14042] Improve SparkHDFS and SparkS3 documentation

[dolfinus]

Change Summary

Add Prerequisites section to SparkHDFS and SparkS3 documentation.

Related issue number

Checklist

• Commit message and PR title is comprehensive
• Keep the change as small as possible
• Unit and integration tests for the changes exist
• Tests pass on CI and coverage does not decrease
• Documentation reflects the changes where applicable
• docs/changelog/next_release/<pull request or issue id>.<change type>.rst file added describing change
  (see CONTRIBUTING.rst for details.)
• My PR is ready to review.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.77%. Comparing base (1f73652) to head (e5c7b47).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #279      +/-   ##
===========================================
- Coverage    94.79%   94.77%   -0.03%     
===========================================
  Files          210      210              
  Lines         8187     8187              
  Branches      1410     1410              
===========================================
- Hits          7761     7759       -2     
- Misses         304      305       +1     
- Partials       122      123       +1     

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