Output cfg-restore-sysrepo failures to console

Also update doc explaining a possible failure.

Change-Id: I0b38041f79f96894ab7b10d78788caf01571485e
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