Fix - Database restore fails with is empty

Short Summary
When the container is built from Docker Hub, the file `WideWorldImporters-Full.bak` is
not copied into the container. This is because docker hub, doesn't support GIT LFS.

Error Message: `The volume on device '/var/opt/sqlserver/WideWorldImporters-Full.bak' is empty.`

Why is it necessary? (Bug fix, feature, improvements?)
- Database was not restoring

How does the change address the issue?
- Using ADD which can access files from URL's

Include a link to the ticket, if any.
- docker/hub-feedback#500

Dockerfile

@@ -6,9 +6,9 @@ RUN mkdir /var/opt/sqlserver
 
 # copy attach-db.sh into container
 COPY restore-db.sh /var/opt/sqlserver
- 
-# copy backupfile
-COPY ./database/WideWorldImporters-Full.bak /var/opt/sqlserver
+
+# USE ADD 
+ADD https://github.com/aleta-systems/aletasystems.role.data.engineer.phase1/raw/master/database/WideWorldImporters-Full.bak /var/opt/sqlserver/
 
 # set script executable
 RUN ["chmod", "+x", "/var/opt/sqlserver/restore-db.sh"]