DOC: Fix typos in doc style.ipynb

[funnycrab]

Simple typo fix.

[codecov]

Codecov Report

Merging #15968 into master will increase coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #15968      +/-   ##
==========================================
+ Coverage      91%   91.01%   +<.01%     
==========================================
  Files         145      145              
  Lines       49581    49581              
==========================================
+ Hits        45122    45124       +2     
+ Misses       4459     4457       -2

Flag	Coverage Δ
#multiple	88.77% <ø> (ø)	⬆️
#single	40.57% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/util/testing.py	81.13% <0%> (+0.18%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 838e09c...09d4196. Read the comment docs.

[TomAugspurger]

Thanks!