DOC: Fix links to OpenPifPaf Guide (#336)

Author: Sven Kreiss

docs/gallery.yml

@@ -130,9 +130,9 @@
   website: https://isa-tools.org/isa-api/content/index.html
   repository: https://github.com/isa-tools/isa-api
 - name: "OpenPifPaf Guide"
-  image: https://vita-epfl.github.io/openpifpaf/_static/logo.png
-  website: https://vita-epfl.github.io/openpifpaf/
-  repository: https://github.com/vita-epfl/openpifpaf
+  image: https://openpifpaf.github.io/_static/logo.png
+  website: https://openpifpaf.github.io
+  repository: https://github.com/openpifpaf/openpifpaf
 - name: "The FAIR Cookbook"
   repository: https://github.com/FAIRplus/the-fair-cookbook
   image: https://raw.githubusercontent.com/FAIRplus/the-fair-cookbook/7b0eba0d01d129ee826e941fd082bad42e6f3151/_static/images/logo/cookbook-logo-small.png