Accessibility fixes to issues found in axe report - #493

Found these issues via a axe scan on Ramp demo site;

• Ensures <dt> and <dd> elements are contained by a <dl>. Description list item does not have a <dl> parent element in MetadataDisplay component
• Ensures elements with an ARIA role that require child roles contain them. Element has children which are not allowed: li[aria-label] in the StructuredNavigation component
• Ensures every HTML document has a lang attribute. The element does not have a lang attribute in the demo implementation page