Theme and Direction switchers on the documentation website

[adamstankiewicz]

The Paragon documentation website now supports a "Settings" pane accessible from the gear icon in the header, with 2 options:

• Theme switcher. May be used to switch between the default Open edX theme and the edX.org theme.
• Direction switcher. May be used to toggle between left-to-right and right-to-left. Note: this feature is in beta. If there are any style issues regarding RTL support, please file an issue.

A third setting is in the works as well... a Language switcher! 👀 See this ADR on i18n for more details.