* latest PlaidML-GPU updates for 0.26

* More theme updates

* Cleaner theme to match site

* Update ngraph_theme

* Update Release Notes page for 0.26

* update theme WIP

* Update theme w/feedback

* Add top navigation menu

* more theme customization and cleanup

* Refine more details on new ngraph theme

* Refine some xsys font-kerning

* Theme updates

* Add latest release notes

* Update HE transformer doc

* Fix rendering

* Resolve doc build warnings

* Add doc versions

* test code removed

* remove test code