Fix Vector* mixin's docstring

[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 and coverable lines are covered by tests :white_check_mark:

Comparison is base (cc6d12e) 83.21% compared to head (624b1df) 83.21%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #404 +/- ## ======================================= Coverage 83.21% 83.21% ======================================= Files 96 96 Lines 11429 11429 ======================================= Hits 9511 9511 Misses 1918 1918 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.