nfsroot: fix microvm.shares.*.tag path

hosts/containers/nfsroot/default.nix

@@ -14,7 +14,7 @@ in {
     } ] ++ map (dir: {
       source = "/var/lib/microvms/${config.networking.hostName}/${dir}";
       mountPoint = "/${dir}";
-      tag = dir;
+      tag = builtins.baseNameOf dir;
       proto = "virtiofs";
       socket = "${builtins.baseNameOf dir}.socket";
     }) [ "etc" "home" "var" "var/lib/nfsroot/dacbert" "var/lib/nfsroot/riscbert" "var/lib/dump-dvb/whoopsie" ];