Add nextcloud app.

apps/nextcloud/manifest.yaml

@@ -0,0 +1,8 @@
+name: nextcloud
+install: true
+description: Nextcloud is a suite of client-server software for creating and using file hosting services.
+version: 1.0.0
+icon: https://nextcloud.com/wp-content/uploads/2022/10/nextcloud-logo-blue-transparent.svg
+requires:
+  - name: redis
+  - name: postgres