update keep-alive api with array syntax (#973)

Author: jkzing

Diff for: src/v2/api/index.md

@@ -2107,8 +2107,8 @@ All lifecycle hooks automatically have their `this` context bound to the instanc
 ### keep-alive
 
 - **Props:**
-  - `include` - string or RegExp. Only components matched by this will be cached.
-  - `exclude` - string or RegExp. Any component matched by this will not be cached.
+  - `include` - string or RegExp or Array. Only components matched by this will be cached.
+  - `exclude` - string or RegExp or Array. Any component matched by this will not be cached.
 
 - **Usage:**
 
@@ -2147,7 +2147,7 @@ All lifecycle hooks automatically have their `this` context bound to the instanc
 
   > New in 2.1.0
 
-  The `include` and `exclude` props allow components to be conditionally cached. Both props can either be a comma-delimited string or a RegExp:
+  The `include` and `exclude` props allow components to be conditionally cached. Both props can be a comma-delimited string, a RegExp or an Array:
 
   ``` html
   <!-- comma-delimited string -->
@@ -2159,6 +2159,11 @@ All lifecycle hooks automatically have their `this` context bound to the instanc
   <keep-alive :include="/a|b/">
     <component :is="view"></component>
   </keep-alive>
+
+  <!-- Array (use v-bind) -->
+  <keep-alive :include="['a', 'b']">
+    <component :is="view"></component>
+  </keep-alive>
   ```
 
   The match is first checked on the component's own `name` option, then its local registration name (the key in the parent's `components` option) if the `name` option is not available. Anonymous components cannot be matched against.