Issue #3269284 by RenatoG: Improve the hook helper with all information...

      $output .= '<dt>' . t("To add a class to a block, simply visit that block's configuration page at Administration » Structure » Block Layout and click on Configure of the desired block.") . '</dt>';

      $output .= '<dt>' . t('The max-length by default is 255, after the 2.0.x version there is a Global Settings Page and you can modify if you need at: <a href="/admin/config/content/block-class/settings">Configuration » Content authoring » Block Class</a>') . '</dt>';

      $output .= '</dl>';

      $output .= '<h3>' . t('Global Configuration') . '</h3>';

      $output .= '<dl>';

      $output .= '<dt>' . t('Inside of global settings there are some possibilities to be used. The "Default Case" is a field to select a standard of your classes. So if you select "Uppercase and Lowercase" but cases will be accepted. If you select "Uppercase" all classes will be added using uppercase and if you select "Lowercase" all classes added will be added using lowercase. Attention, if you change to only lowercase or only uppercase when save the block all block classes will be updated.') . '</dt>';

      $output .= '<dt>' . t('Field Type: By default the block class is using the field type as a "texfield", with that configuration you can select textarea as well, it\'s recommended if you have many classes per block') . '</dt>';

      $output .= '<dt>' . t('The max-length by default is 255, after the 2.0.x version there is a Global Settings Page and you can modify if you need at: /admin/config/content/block-class/settings or Configuration » Content authoring » Block Class') . '</dt>';

      $output .= '<dt>' . t('Allow only letters and numbers: If you select this checkbox the blocks will be filtered to allows only letters and numbers') . '</dt>';

      $output .= '</dl>';

      $output .= '<h3>' . t('Block List') . '</h3>';

      $output .= '<dl>';

      $output .= '<dt>' . t('You\'re able to see that at admin/config/content/block-class/list , on this list you\'re able to see all blocks that have block class added, and on this table you also can edit easily your block classes and if you need you can remove the block class using this page as well') . '</dt>';

      $output .= '</dl>';

      $output .= '<h3>' . t('Bulk Operations') . '</h3>';

      $output .= '<dl>';

      $output .= '<dt>' . t('There is a Bulk Operation to update classes automatically to help. To do this, you can go to Administration » Configuration » Content authoring » Block Class » Bulk Operations and there you can select some options:') . '</dt>';

      $output .= '<dt>' . t('Insert classes: With that option you can insert a class by default in all blocks that you have') . '</dt>';

      $output .= '<dt>' . t('Update class: With that option you can insert a current class that you have in the field "Current class" and in the other field "New class" you can insert the new class that you want to use. After this you\'ll be redirected to another page to review that and update all classes.') . '</dt>';

      $output .= '<dt>' . t('Delete all block classes: With this option, the bulk operation will remove all block classes on blocks. After this form you\'ll be redirected to another page to confirm that operation') . '</dt>';

      $output .= '</dl>';

      $output .= '<h3>' . t('Block Class Documentation') . '</h3>';

      $output .= '<dl>';

      $output .= '<dt>' . t('To see more information feel free to see our documentation at <a href="https://www.drupal.org/docs/contributed-modules/block-class" target="blank">Drupal » Contributed Projects » Block Class</a>') . '</dt>';