content: Fix imported posts (markdown syntax, article types)

The auto-importer has created several issues with the markdown syntax which
needed manual fixing. Additionally quite a lot of event annoucements were
categorized as article.

content/blog/2007/2007-09-18-bildungswerk-nerdlobbyismus-howto/index.md

@@ -1,7 +1,7 @@
 ---
 authors:
 - ccchh-archiv
-categories: article
+categories: event
 draft: false
 lastmod: '2007-09-18T15:13:58+02:00'
 publishDate: '2007-09-18T15:13:58+02:00'
@@ -11,7 +11,6 @@ title: 'Bildungswerk: Nerdlobbyismus-HowTo'
 Am **Mittwoch**, dem **26.09.2007** ab ca. **19:00 Uhr** berichtet Hanno
 Zulla im Rahmen des Hamburger Bildungswerkes
 
-
 * Mehr in [Hannos Blog][2]
 * [Übersicht zum Bildungswerk][3]
 * [Anfahrtsbeschreibung][4]