syntax fix [skip ci]

framework/db/ActiveRecord.php

@@ -53,7 +53,7 @@ use yii\helpers\StringHelper;
  * * Using the `new` operator to create a new, empty object
  * * Using a method to fetch an existing record (or records) from the database
  *
- * Here is a short teaser how working with an ActiveRecord looks like:
+ * Below is an example showing some typical usage of ActiveRecord:
  *
  * ```php
  * $user = new User();

framework/grid/Column.php

@@ -32,7 +32,7 @@ class Column extends Object
      */
     public $footer;
     /**
-     * @var callable This is a callable that will be used to generated the content of each cell.
+     * @var callable This is a callable that will be used to generate the content of each cell.
      * The signature of the function should be the following: `function ($model, $key, $index, $column)`.
      * Where `$model`, `$key`, and `$index` refer to the model, key and index of the row currently being rendered
      * and `$column` is a reference to the [[Column]] object.