Update typo in p-median example

[nickbearman]

Thanks for the example - I spotted a typo :-)

[codecov]

Codecov Report

Merging #275 (607e857) into main (85ec22f) will increase coverage by 0.2%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##            main    #275     +/-   ##
=======================================
+ Coverage   67.6%   67.8%   +0.2%     
=======================================
  Files         24      24             
  Lines       2717    2717             
  Branches     591     591             
=======================================
+ Hits        1836    1841      +5     
+ Misses       792     783      -9     
- Partials      89      93      +4     

Impacted Files	Coverage Δ
spopt/_version.py	33.8% <0.0%> (+1.5%)	⬆️

[gegen07]

Thanks, @nickbearman for your first contribution on spopt! 🎉 :