Issue #3153394 by azslay, joegraduate, hedrickbt, Shoshana Mayden: Document...

Issue #3153394 by azslay, joegraduate, hedrickbt, Shoshana Mayden: Document route:<button> in LinkWidget help text

core/modules/link/src/Plugin/Field/FieldWidget/LinkWidget.php

@@ -216,12 +216,12 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen
     // element prefix and description.
     if (!$this->supportsExternalLinks()) {
       $element['uri']['#field_prefix'] = rtrim(Url::fromRoute('<front>', [], ['absolute' => TRUE])->toString(), '/');
-      $element['uri']['#description'] = $this->t('This must be an internal path such as %add-node. You can also start typing the title of a piece of content to select it. Enter %front to link to the front page. Enter %nolink to display link text only.', ['%add-node' => '/node/add', '%front' => '<front>', '%nolink' => '<nolink>']);
+      $element['uri']['#description'] = $this->t('This must be an internal path such as %add-node. You can also start typing the title of a piece of content to select it. Enter %front to link to the front page. Enter %nolink to display link text only. Enter %button to display keyboard-accessible link text only.', ['%add-node' => '/node/add', '%front' => '<front>', '%nolink' => '<nolink>', '%button' => 'route:<button>']);
     }
     // If the field is configured to allow both internal and external links,
     // show a useful description.
     elseif ($this->supportsExternalLinks() && $this->supportsInternalLinks()) {
-      $element['uri']['#description'] = $this->t('Start typing the title of a piece of content to select it. You can also enter an internal path such as %add-node or an external URL such as %url. Enter %front to link to the front page. Enter %nolink to display link text only.', ['%front' => '<front>', '%add-node' => '/node/add', '%url' => 'http://example.com', '%nolink' => '<nolink>']);
+      $element['uri']['#description'] = $this->t('Start typing the title of a piece of content to select it. You can also enter an internal path such as %add-node or an external URL such as %url. Enter %front to link to the front page. Enter %nolink to display link text only. Enter %button to display keyboard-accessible link text only.', ['%front' => '<front>', '%add-node' => '/node/add', '%url' => 'http://example.com', '%nolink' => '<nolink>', '%button' => 'route:<button>']);
     }
     // If the field is configured to allow only external links, show a useful
     // description.