update vm file, fix README, add working dir in module

vm-mail-quota-warning.py

@@ -0,0 +1,38 @@
+{ pkgs, ... }:
+{
+
+  environment.etc."mail-quota-warning-secrets.yml".text = ''
+    accounts:
+      - name: Sales
+        imap_server: mail.example.com
+        imap_port: 993
+        username: sales@example.com
+        password: secret
+
+      - name: Support
+        imap_server: mail.example.com
+        imap_port: 993
+        username: support@example.com
+        password: secret
+
+    mail:
+      smtp_server: mail.example.com
+      smtp_port: 587
+      smtp_username: monitoring@example.com
+      smtp_password: secret
+      from_address: monitoring@example.com
+      recipients:
+        - admin1@example.com
+        - admin2@example.com
+  '';
+
+  services.mail-quota-warning = {
+    enable = true;
+    settings = {
+      CHECK_INTERVAL_DAYS = 7;
+      QUOTA_WARNING_THRESHOLD_PERCENT = 80;
+    };
+    secretFile = /etc/mail-quota-warning-secrets.yml;
+  };
+
+}