Fix backlink documentation
In the example the link keyword is omitted and the example as presented here errors on migration
@@ -110,7 +110,7 @@ to traverse a link in the *reverse* direction.
type User {
property name -> str;
- blog_posts := .<author[is BlogPost]
+ multi link blog_posts := .<author[is BlogPost]
}
The ``User.blog_posts`` expression above uses the *backlink operator* ``.<`` in
