Revert "video and app links for the beipackzettel"

This reverts commit 36bb4f9c.

app/_index.md

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-title: Placeholder for APP link from the Beipackzettel
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-# APP INSTALLATION INSTRUCTIONS GOx HERE

vid/_index.md

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-title: Placeholder for video link from the Beipackzettel
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-# ASSEMBLY VIDEO GOES HERE

[Phileas]

@G Just reverted this since this is rendering the site quite ugly. I hope that is ok.

PS: Should this maybe be under /en/app?