Merge fort-nix/nix-bitcoin#397: backups: make extraFiles list of strings

c483f1694d examples: correct localBackups scp command (nixbitcoin)
cb54891484 backups: make extraFiles list of strings (nixbitcoin)

Pull request description:

ACKs for top commit:
  erikarvstedt:
    ACK c483f1694d

Tree-SHA512: cb178382655e70aaf85f5930ec7a2c631c28e4c447d0b5d02d973eb73e3bd902ab091cc496d79efbfba5355b9574cb5ba6dd5a4d395b0cda4e3da715fd88d9c5

examples/configuration.nix

@@ -211,7 +211,7 @@
   # services.backups.enable = true;
   #
   # You can pull the localBackups folder with
-  # `scp bitcoin-node:/var/lib/localBackups /my-backup-path/`
+  # `scp -r bitcoin-node:/var/lib/localBackups /my-backup-path/`
   # Alternatively, you can also set a remote target url, for example
   # services.backups.destination = "sftp://user@host[:port]/[relative|/absolute]_path";
   # Supply the sftp password by appending the FTP_PASSWORD environment variable

modules/backups.nix

@@ -31,11 +31,9 @@ let
       description = "List of database names to backup.";
     };
     extraFiles = mkOption {
-      type = types.lines;
-      default = "";
-      example = ''
-        /var/lib/nginx
-      '';
+      type = types.listOf types.str;
+      default = [];
+      example = [ "/var/lib/nginx" ];
       description = "Additional files to be appended to filelist.";
     };
   };
@@ -62,7 +60,7 @@ let
     ${builtins.concatStringsSep "\n" postgresqlBackupPaths}
 
     # Extra files
-    ${cfg.extraFiles}
+    ${builtins.concatStringsSep "\n" cfg.extraFiles}
 
     # Exclude all unspecified files and directories
     - /