DOC: spellchecked io.rst

[tommyod]

Spellcheck of the docs, specifically of io.rst.
I did not read everything thoroughly, but I believe the suggested changes will help enforce a greater level of consistency in the docs.

• Backticks `` around Series, DataFrame.
• Added some function references, i.e. :meth:`~DataFrame.method`.
• Consistency of booleans, typsetting as False instead of False or False.
• Minor rephrasing of sentences, spelling, periods, colons etc.

Cheers!

[codecov]

Codecov Report

Merging #19660 into master will increase coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #19660      +/-   ##
==========================================
+ Coverage   91.58%   91.59%   +<.01%     
==========================================
  Files         150      150              
  Lines       48806    48806              
==========================================
+ Hits        44701    44703       +2     
+ Misses       4105     4103       -2

Flag	Coverage Δ
#multiple	89.96% <ø> (ø)	⬆️
#single	41.73% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/util/testing.py	83.85% <0%> (+0.2%)	⬆️

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[jorisvandenbossche]

Thanks a lot for this!

I have my doubts a about the need to quote all occurrences of 'DataFrame', but will open a separate issue for that.

[jreback]

thanks @tommyod

I kind of like the formatting when reading with quoted DataFrame/Series.