Provide example usage

README.md

@@ -1,2 +1,14 @@
 # linode_instance
 
+## Usage
+
+```
+module "test1" {
+  source = "git::https://git.fdragon.com/TerraformModules/linode_instance.git"
+  authorized_keys = [
+    linode_sshkey.example.ssh_key,
+  ]
+  host_name   = "hellow-world"
+  domain_name = "example.com"
+}
+```