Issue #3093275: Token (& token type) machine name requirements

Closes #3093275

src/Entity/TokenCustom.php

@@ -59,7 +59,7 @@ class TokenCustom extends ContentEntityBase implements TokenCustomInterface {
   public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
     $fields['machine_name'] = BaseFieldDefinition::create('string')
       ->setLabel(t('Machine name ID'))
-      ->setDescription(t('A unique machine-readable name for this token. It must only contain lowercase letters, numbers, and underscores.'))
+      ->setDescription(t('A unique machine-readable name for this token. It must only contain lowercase letters, numbers, hyphens, and underscores.'))
       ->setSetting('max_length', 64)
       ->setDisplayOptions('form', [
         'label' => 'hidden',