docs: add an example: How to use RxPY to prepare batches by maximum bytes count.

[bednar]

Closes #392

Proposed Changes

Added an example: How to use RxPY to prepare batches by maximum bytes count.

Checklist

• CHANGELOG.md updated
• Rebased/mergeable
• A test has been added if appropriate
• pytest tests completes successfully
• Commit messages are in semantic format
• Sign CLA (if not already signed)

[codecov-commenter]

Codecov Report

Merging #397 (ec9a781) into master (7a24f63) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #397   +/-   ##
=======================================
  Coverage   90.52%   90.52%           
=======================================
  Files          39       39           
  Lines        3355     3355           
=======================================
  Hits         3037     3037           
  Misses        318      318           

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[powersj]

agreed on not modifying the underlying library for this. The example looks good!

[powersj]

@rhajek thoughts on this one?

[rhajek]

The example as a workaround is ok.

[powersj]

The example as a workaround is ok.

Thanks

@bednar can you update the README change for this PR and we can land this?

[bednar]

@powersj the sources are rebased and updated to RxPY v4.0.4

[powersj]

thank you!