Fix a link to subgroup doc from manifest doc

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

doc/user/project/import/manifest.md

@@ -5,7 +5,7 @@ based a manifest file like the one used by the Android repository.
 
 
 >**Note:** 
-This feature requires [subgroups](user/group/subgroups/index.md) to be supported by your database. 
+This feature requires [subgroups](../../group/subgroups/index.md) to be supported by your database. 
 
 You can do it by following next steps: