Update landing page CTAs to proper docs pages (#433)

website/components/subnav/index.jsx

@@ -17,7 +17,7 @@ export default function ProductSubnav() {
           text: 'GitHub',
           url: `https://www.github.com/hashicorp/${productSlug}`,
         },
-        { text: 'Download', url: '#' },
+        { text: 'Download', url: '/docs/getting-started/building' },
       ]}
       currentPath={router.pathname}
       menuItemsAlign="right"

website/pages/home/index.jsx

@@ -9,12 +9,12 @@ export default function HomePage() {
         links={[
           {
             text: 'Download',
-            url: '#',
+            url: '/docs/getting-started/building',
             type: 'download',
           },
           {
             text: 'Get Started',
-            url: '/docs/introduction',
+            url: '/docs/getting-started',
             type: 'inbound',
           },
         ]}