feat(mailerlite): add spam complaint trigger

packages/docs/pages/apps/mailerlite/triggers.md

@@ -0,0 +1,12 @@
+---
+favicon: /favicons/mailerlite.svg
+items:
+  - name: Spam Complaint
+    desc: Triggers when a subscriber reports an email as spam.
+---
+
+<script setup>
+  import CustomListing from '../../components/CustomListing.vue'
+</script>
+
+<CustomListing />