docs: add docs for vector.zip

[Saransh-cpp]

Description

Kindly take a look at CONTRIBUTING.md.

Please describe the purpose of this pull request. Reference and link to any relevant issues or pull requests.

Checklist

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't any other open Pull Requests for the required change?
• Does your submission pass pre-commit? ($ pre-commit run --all-files or $ nox -s lint)
• Does your submission pass tests? ($ pytest or $ nox -s tests)
• Does the documentation build with your changes? ($ cd docs; make clean; make html or $ nox -s docs)
• Does your submission pass the doctests? ($ xdoctest ./src/vector or $ nox -s doctests)

Before Merging

• Summarize the commit messages into a brief review of the Pull request.

[codecov-commenter]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (e612e95) 83.21% compared to head (87021a3) 83.21%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #390   +/-   ##
=======================================
  Coverage   83.21%   83.21%           
=======================================
  Files          96       96           
  Lines       11429    11429           
=======================================
  Hits         9511     9511           
  Misses       1918     1918           

Files	Coverage Δ
src/vector/backends/awkward.py	83.86% <ø> (ø)

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[Saransh-cpp]

Related to #385