DOC: fixes after #17503 and #17491

[jorisvandenbossche]

There was still a doc build error (df was not defined due to a missing 'i' in 'ipython')

[codecov]

Codecov Report

Merging #17541 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #17541      +/-   ##
==========================================
- Coverage   91.25%   91.23%   -0.02%     
==========================================
  Files         163      163              
  Lines       49606    49606              
==========================================
- Hits        45266    45257       -9     
- Misses       4340     4349       +9

Flag	Coverage Δ
#multiple	89.01% <ø> (ø)	⬆️
#single	40.19% <ø> (-0.07%)	⬇️

Impacted Files	Coverage Δ
pandas/core/base.py	96.01% <ø> (ø)	⬆️
pandas/io/gbq.py	25% <0%> (-58.34%)	⬇️
pandas/core/frame.py	97.77% <0%> (-0.1%)	⬇️

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[jreback]

thanks!