update config with NGINX_AUTH_PORT_MAP

debian/ai-auth-server.conf

@@ -32,3 +32,10 @@ LDAP_BIND_DN = 'cn=manager, o=Anarchy'
 
 with open('/etc/ldap.secret') as fd:
     LDAP_BIND_PW = fd.read().strip()
+
+# Port mapping for the dovecot service on backends.
+NGINX_AUTH_PORT_MAP = {
+    'pop3': 10110,
+    'imap': 10143
+}
+