ENGCOM-1476: fixed documentation about viewModels. The key in xml should be view_m… #15067

Author: VladimirZaets

app/code/Magento/Backend/Block/Template.php

@@ -17,10 +17,12 @@
  * Example:
  * <block name="my.block" class="Magento\Backend\Block\Template" template="My_Module::template.phtml" >
  *      <arguments>
- *          <argument name="viewModel" xsi:type="object">My\Module\ViewModel\Custom</argument>
+ *          <argument name="view_model" xsi:type="object">My\Module\ViewModel\Custom</argument>
  *      </arguments>
  * </block>
  *
+ * Your class object can then be accessed by doing $block->getViewModel()
+ *
  * @api
  * @SuppressWarnings(PHPMD.NumberOfChildren)
  * @since 100.0.2