Added README.md for roles

Signed-off-by: Tuan-Dat Tran <tuan-dat.tran@tudattr.dev>

roles/common/README.md

@@ -0,0 +1,49 @@
+# Ansible Role: common
+
+This role configures a baseline set of common configurations for Debian-based systems.
+
+## Requirements
+
+None.
+
+## Role Variables
+
+Available variables are listed below, along with default values (see `vars/main.yml`):
+
+```yaml
+# The hostname to configure.
+hostname: "new-host"
+
+# A list of extra packages to install.
+extra_packages:
+  - "htop"
+  - "ncdu"
+  - "stow"
+  - "unzip"
+```
+
+## Dependencies
+
+None.
+
+## Example Playbook
+
+Including an example of how to use your role (for instance, with variables passed in as parameters) is always nice for users too:
+
+```yaml
+- hosts: servers
+  roles:
+    - role: common
+      hostname: "my-new-host"
+      extra_packages:
+        - "vim"
+        - "curl"
+```
+
+## License
+
+MIT
+
+## Author Information
+
+This role was created in 2025 by [TuDatTr](https://codeberg.org/tudattr/).