Continue structural port from Spring Boot to Undertow

- Configuration options
- Configuration documentation

docs/threepids/medium/email/smtp-connector.md

@@ -5,15 +5,17 @@ Connector ID: `smtp`
 
 ## Configuration
 ```yaml
-threepid.medium.email:
-  identity:
-    from: 'identityServerEmail@example.org'
-    name: 'My Identity Server'
-  connectors:
-    smtp:
-      host: 'smtpHostname'
-      port: 587
-      tls: 1 # 0 = no STARTLS, 1 = try, 2 = force
-      login: 'smtpLogin'
-      password: 'smtpPassword'
+threepid:
+  medium:
+    email:
+      identity:
+        from: 'identityServerEmail@example.org'
+        name: 'My Identity Server'
+      connectors:
+        smtp:
+          host: 'smtpHostname'
+          port: 587
+          tls: 1 # 0 = no STARTLS, 1 = try, 2 = force
+          login: 'smtpLogin'
+          password: 'smtpPassword'
 ```