doc: fix typo in levicivita doc

[inkydragon]

Broken doctest: https://juliamath.github.io/Combinatorics.jl/dev/api/#Combinatorics.levicivita-Tuple{AbstractVector{%3C:Integer}}

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.18%. Comparing base (d1f949d) to head (705873b).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #180   +/-   ##
=======================================
  Coverage   97.18%   97.18%           
=======================================
  Files           8        8           
  Lines         816      816           
=======================================
  Hits          793      793           
  Misses         23       23           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.