re add slides

docs/slides.md

public/en/slides/index.html

public/feed_rss_created.xml

public/feed_rss_updated.xml

public/search/search_index.json

public/sitemap.xml

public/sitemap.xml.gz

public/slides/index.html

public/veranstaltungen/index.html

slides/beispiel/index.html

slides/beispiel/slides.md

slides/bilder/index.html

slides/bilder/slides.md

slides/lib/reveal/CONTRIBUTING.md

slides/lib/reveal/LICENSE

slides/lib/reveal/README.md

slides/lib/reveal/css/layout.scss

slides/lib/reveal/css/print/paper.scss

slides/lib/reveal/css/print/pdf.scss

slides/lib/reveal/css/reveal.scss