Docs: Add MD for package-latest rule

src/ansiblelint/rules/package_latest.md

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+# package-latest
+
+This rule checks that package managers install software in a controlled, safe manner.
+
+Package manager modules, such as `ansible.builtin.yum`, include a `state` parameter that configures how Ansible installs software.
+In production environments, you should set `state` to `present` and specify a target version to ensure that packages are installed to a planned and tested version.
+
+Setting `state` to `latest` not only installs software, it performs an update and installs additional packages.
+This can result in performance degradation or loss of service.
+If you do want to update packages to the latest version, you should also set the `update_only` parameter to `true` to avoid installing additional packages.
+
+## Problematic Code
+
+```yaml
+---
+- name: Example playbook
+  hosts: localhost
+  tasks:
+    - name: Install Ansible
+      ansible.builtin.yum: name=ansible state=latest # <- Installs the latest package.
+
+    - name: Install Ansible-lint
+      ansible.builtin.pip: name=ansible-lint
+      args:
+        state: latest # <- Installs the latest package.
+
+    - name: Install some-package
+      ansible.builtin.package:
+        name: some-package
+        state: latest # <- Installs the latest package.
+
+    - name: Install Ansible with update_only to false
+      ansible.builtin.yum:
+        name: sudo
+        state: latest
+        update_only: false # <- Updates and installs packages.
+```
+
+## Correct Code
+
+```yaml
+---
+- name: Example playbook
+  hosts: localhost
+  tasks:
+    - name: Install Ansible
+      ansible.builtin.yum: name=ansible-2.12.7.0 state=present # <- Pins the version to install with yum.
+
+    - name: Install Ansible-lint
+      ansible.builtin.pip: name=ansible-lint
+      args:
+        state: present
+        version: 5.4.0 # <- Pins the version to install with pip.
+
+    - name: Install some-package
+      ansible.builtin.package:
+        name: some-package
+        state: present # <- Ensures the package is installed.
+
+    - name: Update Ansible with update_only to true
+      ansible.builtin.yum:
+        name: sudo
+        state: latest
+        update_only: true # <- Updates but does not install additional packages.
+```