add source link
+<!-- Vendored from https://github.com/executablebooks/sphinx-book-theme/blob/3736580774c84dcf8a2d84085ba022cc57552704/sphinx_book_theme/layout.html -->
+
{% extends "pydata_sphinx_theme/layout.html" %}
{% set is_single_page = (theme_single_page == True) or (theme_single_page == "True") %}
