doc for PickPostalCode vue component

src/Bundle/ChillMainBundle/Resources/public/vuejs/PickPostalCode/PickPostalCode.md

@@ -1,4 +1,29 @@
 # Pickpostalcode
 
+Allow to pick a postal code.
+
+In use with module `mod_pick_postal_code`, associated  with `PickPostalCodeType` in php.
+
 ## Usage
-    <PickPostalCode />
+    
+    `<pick-postal-code @select-city="onCitySelected" @removeCity="onCityRemoved" :picked="city"></pick-postal-code>`
+
+## Props
+
+* `picked`: the city picked. A javascript object (a city). Null if empty.
+* `country`: country to restraint search on picked. May be null.
+
+## Emits
+
+### `selectCity`
+
+When a city is onCitySelected.
+
+Argument: a js object, representing a city
+
+### `removeCity`
+
+When a city is removed.
+
+
+Argument: a js object, representing a city