Add attributions example

Showing how to dynamically change collapsed/collapsible properties for ≠
map sizes.

examples/attributions.js

@@ -0,0 +1,33 @@
+goog.require('ol.Map');
+goog.require('ol.View');
+goog.require('ol.control');
+goog.require('ol.control.Attribution');
+goog.require('ol.layer.Tile');
+goog.require('ol.source.OSM');
+
+var attribution = new ol.control.Attribution({
+  collapsible: false
+});
+var map = new ol.Map({
+  layers: [
+    new ol.layer.Tile({
+      source: new ol.source.OSM()
+    })
+  ],
+  controls: ol.control.defaults({ attribution: false }).extend([attribution]),
+  renderer: exampleNS.getRendererFromQueryString(),
+  target: 'map',
+  view: new ol.View({
+    center: [0, 0],
+    zoom: 2
+  })
+});
+
+function checkSize() {
+  var small = map.getSize()[0] < 600;
+  attribution.setCollapsible(small);
+  attribution.setCollapsed(small);
+}
+
+$(window).on('resize', checkSize);
+checkSize();