Rename all j2 files to templates

Not according to convention, but it reads better.

playbook-apprise.yml

@@ -37,7 +37,7 @@
 
     - name: "Copy apprise config"
       ansible.builtin.template:
-        src: "./files/{{ app_name }}/server.cfg.j2"
+        src: "./files/{{ app_name }}/server.template.cfg"
         dest: "{{ config_dir }}/server.cfg"
         owner: "{{ app_user }}"
         group: "{{ app_user }}"