Update deprecated 'pygments' configuration option

Renamed to 'highlighter' per Jekyll v2.5.1 warning
Fix Mac/Linux download link per PR #4 from @erlendleganger
Copyfit call to action in hero unit
Clarify that main links point to client distribution
Update 2.0 documentation
Create CNAME
Remove DITA-OT Day from navigation
Remove .html from links to clean URIs
Remove .html from links to clean URIs
Fix TOC highlight
Merge branch 'master' of github.com:dita-ot/dita-ot.github.io