docker(role): update README

Document Debian 12 support, enhance wording, bring structure in line
with the READMEs of more modern roles and remove unnecessary sections.

roles/docker/README.md

@@ -1,26 +1,22 @@
 # Role `docker`
 
-Makes sure Docker Engine and other related packages are installed from the Docker repos on the specified hosts.
-For details see: [`tasks/main/02_docker_install.yaml`](./tasks/main/02_docker_install.yaml).
+Ensures the Docker Engine and other related packages are installed from the Docker repos.
+For detailed list of packages see: [`tasks/main/02_docker_install.yaml`](./tasks/main/02_docker_install.yaml).
 
 ## Supported Distributions
 
 The following distributions are supported:
 
 - Debian 11
+- Debian 12
 
 ## Required Arguments
 
 None.
 
-## Updates
+## Optional Arguments
 
-This role doesn't handle updates.
-However it uses the system package manager for installing Docker Engine and the other related packages, so when you're making sure the system packages are up-to-date, you're handling updates for the packages installed by this role as well.
-
-## `hosts`
-
-The `hosts` for this role need to be the machines for which you want to make sure Docker Engine and other related packages are installed from the Docker repos.
+None.
 
 ## Links & Resources