Added README.md for roles

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

roles/k3s_storage/README.md

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+# k3s_storage Ansible Role
+
+This role installs and configures a k3s node with storage-specific taints and labels.
+
+## Role Variables
+
+- `k3s.loadbalancer.default_port`: The port of the k3s loadbalancer. Defaults to `6443`.
+- `k3s_token`: The token to join the k3s cluster. This is a required variable.
+- `hostvars['k3s-loadbalancer'].ansible_default_ipv4.address`: The IP address of the k3s loadbalancer. This is discovered automatically from the host with the name `k3s-loadbalancer`.
+
+## Tasks
+
+The main task includes the following files:
+
+- `requirements.yml`:
+  - Updates and upgrades system packages.
+  - Installs `open-iscsi` and `nfs-common`.
+  - Starts and enables the `open-iscsi` service.
+- `installation.yml`:
+  - Downloads the k3s installation script.
+  - Installs k3s on the node with the following configurations:
+    - Taint: `storage=true:NoExecute`
+    - Label: `longhorn=true`
+
+## Handlers
+
+- `Restart k3s`: Restarts the k3s service.
+
+## Usage
+
+Here is an example of how to use this role in a playbook:
+
+```yaml
+- hosts: k3s_storage_nodes
+  roles:
+    - role: k3s_storage
+      vars:
+        k3s_token: "your_k3s_token"
+```