Adding aria-current to the anchor tag of the selected item for VerticalNavigation (#2748)

* add aria-current

* use undefined

Co-authored-by: Stephen James <[email protected]>

Author: Prophetess

components/vertical-navigation/__docs__/__snapshots__/storybook-stories.storyshot

@@ -22,6 +22,7 @@ exports[`DOM snapshots SLDSVerticalNavigation DOM Snapshot 1`] = `
           className="slds-nav-vertical__item slds-is-active"
         >
           <a
+            aria-current={true}
             aria-describedby="sample-navigation-reports"
             className="slds-nav-vertical__action"
             data-id="recent_reports"
@@ -169,6 +170,7 @@ exports[`DOM snapshots SLDSVerticalNavigation Default 1`] = `
             className="slds-nav-vertical__item slds-is-active"
           >
             <a
+              aria-current={true}
               aria-describedby="sample-navigation-reports"
               className="slds-nav-vertical__action"
               data-id="recent_reports"

components/vertical-navigation/private/item.jsx

@@ -34,6 +34,7 @@ const Item = (props) => (
 			href={props.item.url || 'javascript:void(0);'} // eslint-disable-line no-script-url
 			className="slds-nav-vertical__action"
 			aria-describedby={props.categoryId}
+			aria-current={props.isSelected ? true : undefined}
 			onClick={(event) => {
 				handleClick(event, props);
 			}}