Update versions in README.md with pre-commit

Currently, versions in README.md need to be manually updated, and we
check it's done with a bash script.

Add a small utility playbook to add versions in README.md from their
actual default values, automatically.
This is done in pre-commit, and replace the scripted check ; instead it
will autofix the README.md, and fails in CI if needed.

We switch markdownlint behind the local hooks to gave it the opportunity
to catch a problem with the rendering.

scripts/render_readme_version.yml

@@ -0,0 +1,22 @@
+#!/usr/bin/env ansible-playbook
+---
+- name: Update README.md versions
+  hosts: localhost
+  connection: local
+  gather_facts: false
+  vars:
+    fallback_ip: 'bypass tasks in kubespray-defaults'
+  roles:
+  - kubespray-defaults
+  tasks:
+  - name: Include versions not in kubespray-defaults
+    include_vars: "{{ item }}"
+    loop:
+    - ../roles/container-engine/docker/defaults/main.yml
+    - ../roles/kubernetes/node/defaults/main.yml
+    - ../roles/kubernetes-apps/argocd/defaults/main.yml
+  - name: Render versions in README.md
+    blockinfile:
+      marker: '[//]: # {mark} ANSIBLE MANAGED BLOCK'
+      block: "\n{{ lookup('ansible.builtin.template', 'readme_versions.md.j2') }}\n\n"
+      path: ../README.md