Entry Forms
A plain entry names a document relative to the one writing it. An entry may
also carry an explicit title, point at self, or be an external URL — all
three appear in this package's index.
Relative and absolute
An entry starting with / is resolved against the source root rather than
the writing document's directory.
Nested sections
These headings are what a parent toctree lists under this document when
:titlesonly: is not set.
Deeper still
A third level, visible only when the parent's :maxdepth: allows it.