Add iscsi role and docs

Since iscsi supports luks + btrfs over the network and makes for an
amazing networked backup drive we should include that in our default
config.

ansible/arch_iscsi/tasks/main.yml

@@ -0,0 +1,17 @@
+---
+# tasks file for ansible/arch_iscsi
+- name: open-iscsi installed
+  community.general.pacman:
+    name: open-iscsi
+    state: present
+- name: Perform a discovery on freenas.dnet and show available target nodes
+  community.general.open_iscsi:
+    show_nodes: yes
+    discover: yes
+    portal: freenas.dnet
+- name: Enable automatic login for freenas.dnet
+  community.general.open_iscsi:
+    login: true
+    portal: freenas.dnet
+    auto_portal_startup: true
+    target: iqn.2022-02.freenas.dnet:manjaro-backup