CHORE(theme)!: update Git submodule (use df8acc3 instead off 5adda22)

Update Git submodule of theme:
- old ref: theme-hugo_faq.adullact.org@5adda22a
- new ref: theme-hugo_faq.adullact.org@df8acc38

BREAKING CHANGE: update Git submodule on your local repository

hugo-geekdoc-adullact @ df8acc38

-Subproject commit 5adda22a83235a66de631b1bb11c78e9417ca39d
+Subproject commit df8acc382cdce15bd6fc46288c5a3fb2b915f605