README.md in kakine-0.4.0 vs README.md in kakine-0.5.0

@@ -20,12 +20,14 @@
 
     $ gem install kakine
 
 ## Usage
 
-You can define Security Group configuration for OpenStack via YAML format. Like following syntax.
+### Syntax
 
+You can define Security Group configuration for OpenStack in YAML format as the following example.
+
 ```yaml
 app:
   rules:
     - direction: ingress
       protocol: tcp
@@ -42,18 +44,55 @@
       protocol: tcp
       port: 3000
       remote_ip: 0.0.0.0/0
 ```
 
+`port`s and `remote_ip`s may be specified as arrays, in which case the rule is expanded to set of rules with all the combinations of them.
+```yaml
+app:
+  rules:
+    - direction: ingress
+      protocol: tcp
+      port: [80, 443]
+      remote_ip:
+        - 192.0.2.0/24
+        - 198.51.100.0/24
+```
+
+
+Top-level keys whose name both starts and ends with underscores (eg. `_common_`, `_default_`) are considered **meta sections** and do not correspond to security groups.
+These sections are useful to define values that commonly appears throughout the file, used with YAML's anchors and references.
+
+```yaml
+_common_:
+  - &net1 192.0.2.0/24
+  - &net2 198.51.100.0/24
+
+restricted_web:
+  rules:
+  - direction: ingress
+    protocol: tcp
+    port: 80
+    remote_ip: *net1
+  - direction: ingress
+    protocol: tcp
+    port: 80
+    remote_ip: *net2
+  description: Restricted HTTP access
+```
+
+### Authentication configuration
+
 You need to put a configuration file to home directory.
 
 ```sh
 % cat ~/.kakine
 auth_url: "http://your-openstack-endpoint/v2.0"
 username: "admin"
-tenant: "admin"
 password: "admin"
 ```
+
+### Commands
 
 run following command.
 
 ```sh
 $ kakine show -t tenant_name # show Security Group of tenant_name