Layout should be configurable per page

[dgarcia360]

Motivation

The option hide_sidebar_index applies to all the versions of the project. However, the new design does not add a sidebar on the main page, breaking the UI of previous versions that do not have the new landing page design.

To solve this issue, we could decide to show or hide the side-nav per page instead of per project. For example, we can create a new custom directive :full-width: that's added a the top of every file where you don't want to show the sidebar.

This change lets projects have previous documentation versions with sidebar, whereas in new versions the sidebar remains hidden.

Proposal

• Deprecate the theme's option hide_sidebar_index.
• Create a file-wide metadata field :full-width:.