docs(explorer): update README.md (#21)

Author: cedoor

README.md

@@ -154,7 +154,7 @@
         <tr>
             <td>
                 <a href="https://github.com/semaphore-protocol/extensions/tree/main/apps/benchmarks">
-                    benchmarks
+                    Benchmarks
                 </a>
             </td>
             <td>
@@ -163,6 +163,18 @@
                 </a>
             </td>
         </tr>
+        <tr>
+            <td>
+                <a href="https://github.com/semaphore-protocol/extensions/tree/main/apps/explorer">
+                    Explorer
+                </a>
+            </td>
+            <td>
+                <a href="https://explorer.semaphore.pse.dev/">
+                    https://explorer.semaphore.pse.dev/
+                </a>
+            </td>
+        </tr>
     <tbody>
 </table>