README.md in gitlab-triage-0.12.0 vs README.md in gitlab-triage-0.13.0

@@ -18,11 +18,12 @@
 
 Each policy can declare a number of conditions that must all be satisfied before a number of actions are carried out.
 
 ### Defining a policy
 
-Policies are defined in a policy file (by default [.triage-policies.yml](.triage-policies.yml)). The format of the file is [YAML](https://en.wikipedia.org/wiki/YAML).
+Policies are defined in a policy file (by default `./.triage-policies.yml`).
+The format of the file is [YAML](https://en.wikipedia.org/wiki/YAML).
 
 > Note: You can use the [`--init`](#usage) option to add an example [`.triage-policies.yml` file](support/.triage-policies.example.yml) to your project
 
 Select which resource to add the policy to:
 - `issues`
@@ -187,10 +188,67 @@
 conditions:
   labels:
     - feature proposal
 ```
 
-###### Labels over sequences
+###### Labels brace expansion
+
+We could expand the labels by using brace expansion, which is a pattern
+surrounded by using braces: `{}`. For now, we support 2 kinds of brace
+expansion:
+
+1. List: `{ apple, orange }`
+2. Sequence: `{1..4}`
+
+> Note:
+>   - Spaces around the items are ignored.
+>   - Do not rely on the expansion ordering. This is subject to change.
+
+###### List
+
+The name of a label can contain a list of items, written like
+`{ apple, orange }`. For each item, the rule will be duplicated with the new
+label name.
+
+Example:
+
+```yml
+resource_rules:
+  issues:
+    rules:
+      - name: Add missing ~Quality label
+        conditions:
+          labels:
+            - Quality:test-{ gap, infra }
+        actions:
+          labels:
+            - Quality
+```
+
+Which will be expanded into:
+
+```yml
+resource_rules:
+  issues:
+    rules:
+      - name: Add missing ~Quality label
+        conditions:
+          labels:
+            - Quality:test-gap
+        actions:
+          labels:
+            - Quality
+
+      - name: Add missing ~Quality label
+        conditions:
+          labels:
+            - Quality:test-infra
+        actions:
+          labels:
+            - Quality
+```
+
+###### Sequence
 
 The name of a label can contain one or more sequence conditions, written
 like `{0..9}`, which means `0`, `1`, `2`, and so on up to `9`. For each
 number, the rule will be duplicated with the new label name.