DOC: release notes / v0.14.0 edits
DOC: Give KDE a section header

DOC: remove extra slice in hexbin example

DOC: move notes to look nicer
Merge pull request #7054 from TomAugspurger/visualization-cleanup

DOC: cleanup vis docs
BUG: fix reading multi-level index in python parser
Merge pull request #7029 from mcwitt/csv_mi_bug

BUG: fix reading multi-index data in python parser
DOC: fix formatting on plot formattting

DOC: add KDE to other plots

more bits of foramtting
Merge pull request #7062 from TomAugspurger/visualization-doc3

DOC: One more cleanup on visualization.rst
BUG: df.boxplot fails to use existing axis/subplot (#3578)

axes needs to be a plt.Axes object

use ax get_axes() to set axes

Add tests for use of existing axis

Add test for when by is None