Added mail notifications on failure. Needs more work on lib.nix and the services/*.nix.

modules/mail/smtp.nix

@@ -3,11 +3,11 @@
 with lib;
 
 let
-  cfg = config.numbus.services.mail;
+  cfg = config.numbus.mail;
 in
 
 {
-  options.numbus.services.mail = {
+  options.numbus.mail = {
     enable = mkEnableOption "Email sending functionality";
 
     userAddress = mkOption {
@@ -31,7 +31,7 @@ in
     smtpPasswordPath = mkOption {
       description = "The path to a file containing the password that will be use to authenticate to the SMTP server";
       type = types.path;
-      example = "/run/secrets/smtp-password";
+      example = /run/secrets/smtp-password;
     };
 
     fromAddress = mkOption {