put d&d pro-tip back

Signed-off-by: Jari Kolehmainen <jari.kolehmainen@gmail.com>

src/renderer/components/+extensions/extensions.tsx

@@ -293,6 +293,9 @@ export class Extensions extends React.Component {
             label="Install"
             onClick={this.addExtensions}
           />
+          <p className="hint">
+            <Trans><b>Pro-Tip</b>: you can drag & drop extension's tarball here to request installation</Trans>
+          </p>
         </div>
       </div>
     );