D45 docs v06.1 (#300)

* Updating dev guide with gh-pages info for docs

* Moving the Dev Guide up in the TOC pane

* Update dev-guide.md

Added Tyler's correction for pycodestyle.

* Updating ref pages from v4.1 to v6.1

* Update dev-guide.md

Updated command to:  pycodestyle tableauserverclient test samples

* Update versions.md

updated example to use the more compact and elegant: `use_server_version=True`

Author: d45