Fix upstream example dockerfile

Fixes operator-framework#472

Author: ecordell

upstream-example.Dockerfile

@@ -5,7 +5,7 @@ RUN /bin/initializer -o ./bundles.db
 
 FROM scratch
 COPY ["nsswitch.conf", "/etc/nsswitch.conf"]
-COPY --from=builder /build/bundles.db /bundles.db
+COPY --from=builder /bundles.db /bundles.db
 COPY --from=builder /bin/registry-server /registry-server
 COPY --from=builder /bin/grpc_health_probe /bin/grpc_health_probe
 EXPOSE 50051