Update to docs links (#5385)

* Removed old links to Twitter and Slack

* Update navigation links in styling guide to point to the current Uber ride page

* Update navigation links in styling guide and remove GitHub issue button from index page

Author: dyesin

documentation-site/pages/guides/styling.mdx

@@ -105,7 +105,7 @@ export default function Navigation() {
       </li>
       <li>
         <a
-          href="https://www.uber.com/us/en/atg/"
+          href="https://www.uber.com/us/en/ride/"
           className={css({
             textDecoration: "none",
             color: theme.colors.accent,
@@ -181,7 +181,7 @@ export default function Navigation() {
         </StyledLink>
       </li>
       <li>
-        <StyledLink href="https://www.uber.com/us/en/atg/">ATG</StyledLink>
+        <StyledLink href="https://www.uber.com/us/en/ride/">Ride</StyledLink>
       </li>
     </ul>
   );

documentation-site/pages/index.jsx

@@ -55,14 +55,6 @@ const Adopters = (props) => (
         </FlexGridItem>
       ))}
     </FlexGrid>
-    <Button
-      $as="a"
-      href="https://github.com/uber/baseweb/issues/1889"
-      size="compact"
-      kind="secondary"
-    >
-      Please let us know if you are using Base Web!
-    </Button>
   </>
 );