20211011 Home Assistant - master branch - PR 1 of 3

Changes `home_assistant` service definition to:

* Reference ghcr.io containers, and provide options to select tailored
images for Raspberry Pi 3 and 4.
* Places container into Host Mode so it can receive multicast traffic.

Documentation re-organised to clearly separate material relevant to
Hass.io (Home Assistant Core) from Home Assistant Container.

Updates Hass.io material in line with what actually happens when that
version is installed.

Author: Paraphraser

.templates/home_assistant/service.yml

@@ -1,11 +1,10 @@
 home_assistant:
   container_name: home_assistant
-  image: homeassistant/home-assistant:stable
+  image: ghcr.io/home-assistant/home-assistant:stable
+  #image: ghcr.io/home-assistant/raspberrypi3-homeassistant:stable
+  #image: ghcr.io/home-assistant/raspberrypi4-homeassistant:stable
   restart: unless-stopped
-  ports:
-    - "8123:8123"
+  network_mode: host
   volumes:
     - /etc/localtime:/etc/localtime:ro
     - ./volumes/home_assistant:/config
-  #network_mode: host
-