Move single ansible playbook to ansible directory

Make ansible playbook properly- use ansible-galaxy init commands.

ansible/arch_docker/tasks/main.yml

@@ -0,0 +1,15 @@
+---
+# Docker
+- name: Ensure docker installed
+  community.general.pacman:
+    name:
+      - docker
+      - docker-compose
+    state: present
+  become: yes
+- name: Ensure ducoterra in the "docker" group
+  ansible.builtin.user:
+    name: ducoterra
+    groups: docker
+    append: yes
+  become: yes