BUG: fix panel.transpose arguments API bug

only show the ambiguous aliases as opposed to all key-value pairs

add release note
DOC: add bs4/lxml install note to README.rst
Merge pull request #3558 from cpcloud/panel-transpose-args-fix-3556

fix panel tranpose arguments api bug
DOC: minor release.rst changes
Merge pull request #3565 from cpcloud/read-html-readme

DOC: add bs4/lxml install note to README.rst
DOC: readme.rst edits
DOC: more readme.rst edits
DOC: readme.rst edits
DOC: readme.rst
DOC: document non-preservation of dtypes across rows with iterrows
Merge pull request #3569 from cpcloud/iterrows-doc-3566

DOC: document non-preservation of dtypes across rows with iterrows