[ext.screenshot] Specify section for target of screenshot

[attakei]

Overview

Using sphinx_revealjs.ext.screenshot, sphinx-builder generates html-presentations and screenshots of first-section.

By this idea, user can select any section as screenshot from presentation for og-image.

Example

(On top of rst source)

.. revealjs-screenshot::
   :section: /1/1
   :fallback:

• section is fragment parameter of Reveal.js presentation URL.
• fallback is flag to use top-page for screenshot if invalid section is specified.

Inspired

• hayasaka
• Blog of hayasaka's author