static/frontend/unit: add canonical URL shortcut key to shortcuts modal

Change-Id: I318671e5adcb22d574cef14ab2008b5b09a8b8fb
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/345510
Trust: Jamal Carvalho <jamal@golang.org>
Run-TryBot: Jamal Carvalho <jamal@golang.org>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
Reviewed-by: Julie Qiu <julie@golang.org>
diff --git a/static/frontend/unit/main/_modals.tmpl b/static/frontend/unit/main/_modals.tmpl
index 0b5f5d7..77f2167 100644
--- a/static/frontend/unit/main/_modals.tmpl
+++ b/static/frontend/unit/main/_modals.tmpl
@@ -77,6 +77,10 @@
                 <span class="go-Chip go-Chip--inverted ShortcutsDialog-themeAuto">auto</span>
               </td>
             </tr>
+            <tr>
+              <td class="ShortcutsDialog-key"><strong>y</strong> or <strong>Y</strong></td>
+              <td> : Canonical URL</td>
+            </tr>
           </tbody>
         </table>
       </div>