.index is the template of children pages in the subtree

When a directory contains a file named .index, all files in children directories are going to use it as template.

An .index file is a normal html file, except that a few templates get replaced by the server generated content:

• {‌{ post }} gets replaced by the content of the post resolved by the HTML path
• {‌{ nav }} gets replaced by the server generated navbar, which is to be placed anywhere. This template places it next to the title

The role of .index is thus to structure and composite in a relatively minimalistic manner the componants that make up a page of the site.