DOC: Fix heading capitalization in doc/source/whatsnew - part3 (#32550)#33429

Merged

jreback merged 3 commits intopandas-dev:masterfrom

cleconte987:modify_doc/source/whatsnew3

Apr 10, 2020

Commits on Apr 9, 2020

Modify heading capitalizations of files in doc/source/whatsnew (part3)
cleconte987
committed
Previously modified I/O into I/o to be in line with script rules. Now Modify I/o in IO as it is already an exception
cleconte987
committed
Merge remote-tracking branch 'upstream_main_pandas/master' into modify_doc/source/whatsnew3
cleconte987
committed