Track rendered vignette.html; remove from .gitignore

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: erwardenaar

.gitignore

@@ -7,5 +7,4 @@
 dist/
 build/
 *.deb
-docs/vignette.html
 docs/vignette_files/