fix and document backup & restore

README.md

@@ -1,3 +1,9 @@
 # nixos-wiki-infra
 
 This project contains everything to setup yourself a mirror of https://nixos.wiki/
+
+After installing run:
+
+```
+systemctl start wiki-backup.service && systemctl start wiki-restore
+```

modules/nixos-wiki/backup.nix

@@ -55,6 +55,7 @@ in
 
     serviceConfig = {
       ExecStart = [
+        "${pkgs.coreutils}/bin/mkdir -p /var/backup"
         "${pkgs.wget}/bin/wget https://nixos.wiki/images/wikidump.xml.gz -O ${wikiDump}.new"
         "${pkgs.coreutils}/bin/mv ${wikiDump}.new ${wikiDump}"
       ];