[wuerstchen] Fix typo in url (#1495)

* fix name

* fix dataset url and blog url

* revert

Author: kashif

_blog.yml

@@ -2809,7 +2809,7 @@
     - guide
     - nlp
 
-- local: wuertschen
+- local: wuerstchen
   title: "Introducing Würstchen: Fast Diffusion for Image Generation"
   author: dome272
   thumbnail: /blog/assets/wuerstchen/thumbnail.jpg