[DOP-8414] Improve Kafka documentation

[dolfinus]

Change Summary

• Improved documentation - instead of just describing reading and writing options I added notes about how read/write can be performed and what limitations are (dataframe schema and so on). See https://onetl--136.org.readthedocs.build/en/136/connection/db_connection/kafka/read.html and https://onetl--136.org.readthedocs.build/en/136/connection/db_connection/kafka/write.html
• Update prohibited options list to match options type (read & write)
• Fix example of using Kafka.SSLProtocol
• Rename File Reader -> FileDF Reader, as well as Writer

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

Merging #136 (9213fb4) into develop (58f28b2) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop     #136   +/-   ##
========================================
  Coverage    94.29%   94.29%           
========================================
  Files          207      207           
  Lines         7697     7697           
  Branches      1451     1451           
========================================
  Hits          7258     7258           
  Misses         320      320           
  Partials       119      119           

Files Changed	Coverage Δ
onetl/connection/db_connection/kafka/connection.py	98.97% <ø> (ø)
...nnection/db_connection/kafka/kafka_ssl_protocol.py	100.00% <ø> (ø)
onetl/connection/db_connection/kafka/options.py	100.00% <ø> (ø)