Fix missing images on English pages

Hugo only auto-shares page-bundle resources across translations when
each language has its own content directory; with filename-based
translation (index.fr.md / index.en.md in the same folder) a resource
with no language code is assigned to the default language only. Add
.en.-suffixed copies of every image referenced from English pages and
point the English markdown at them.

content/blog/migration-gitlab-gitea/index.en.md

@@ -28,7 +28,7 @@ But several needs emerged:
 
 ## The Overall Architecture
 
-![Architecture](global_architecture.fr.svg)
+![Architecture](global_architecture.en.svg)
 
 ### Tech Stack