Update links broken by move to ref shortcode

There are 2 internationalisation documents, we need to detail which one we
mean in the link that uses it.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>

content/developer/bundle-spec.md

@@ -1194,7 +1194,7 @@ backwards compatibility, and is considered deprecated.
 [Content hand-over]:  {{< ref "content_hand-over.md" >}} 
 [Content type handler]:  {{< ref "content_hand-over.md" >}} 
 [Interface discovery]:  {{< ref "interface_discovery.md" >}} 
-[Internationalization concept design]:  {{< ref "internationalization.md" >}} 
+[Internationalization concept design]:  {{< ref "designs/internationalization.md" >}} 
 [Platform layer]:  {{< ref "applications.md#software-categories" >}} 
 [Preferences]:  {{< ref "preferences-and-persistence.md#preferences-approach" >}} 
 [Security between application bundles]:  {{< ref "security.md#security-between-applications" >}}