Output cfg-restore-sysrepo failures to console

Also update doc explaining a possible failure.

Change-Id: I0b38041f79f96894ab7b10d78788caf01571485e
diff --git a/README.md b/README.md
index 6a9e000..6aaf060 100644
--- a/README.md
+++ b/README.md
@@ -62,6 +62,13 @@
 reboot
 ```
 
+Because `/cfg` is preserved, it can happen that there are data, which are incompatible with the version you are
+uploading. The reason could be that a YANG model got downgraded to an older one (example: cla-sysrepo downgrade). This
+is signalled by the failure of the [`cfg-restore-sysrepo.service`](package/czechlight-cfg-fs/cfg-restore-sysrepo.service) service.
+In this case, one needs to edit the `/cfg/sysrepo/startup.json` file and remove the offending content. The exact errors
+will be shown in the systemd journal and also in the console.
+
+
 ### Initial installation
 
 #### Clearfog
diff --git a/package/czechlight-cfg-fs/cfg-restore-sysrepo.service b/package/czechlight-cfg-fs/cfg-restore-sysrepo.service
index 9fe0c8a..cac0f64 100644
--- a/package/czechlight-cfg-fs/cfg-restore-sysrepo.service
+++ b/package/czechlight-cfg-fs/cfg-restore-sysrepo.service
@@ -10,6 +10,7 @@
 RemainAfterExit=yes
 ExecStart=/bin/sysrepocfg -d startup -f json --import=/cfg/sysrepo/startup.json
 ExecStart=/bin/sysrepocfg -C startup
+StandardOutput=journal+console
 
 [Install]
 WantedBy=multi-user.target