Issue #3113124 by B2F, Kristen Pol: Incorrect API example about default widget override

(cherry picked from commit da4caf4f)

core/modules/field/field.api.php

@@ -53,7 +53,7 @@
 function hook_field_info_alter(&$info) {
   // Change the default widget for fields of type 'foo'.
   if (isset($info['foo'])) {
-    $info['foo']['default widget'] = 'mymodule_widget';
+    $info['foo']['default_widget'] = 'mymodule_widget';
   }
 }