[gnome-photos] help-overlay: Add the shortcut for showing the help overlay itself

[Debarshi Ray <debarshir src gnome org>]

commit 39ed112d6e087ffb84ed8fbf72d071fa2c6713ae
Author: Sabri Ünal <libreajans gmail com>
Date:   Sun Feb 9 18:36:27 2020 +0300

    help-overlay: Add the shortcut for showing the help overlay itself
    
    https://gitlab.gnome.org/GNOME/gnome-photos/-/merge_requests/119

 src/photos-help-overlay.ui | 7 +++++++
 1 file changed, 7 insertions(+)
---
diff --git a/src/photos-help-overlay.ui b/src/photos-help-overlay.ui
index 07d87dd1..b42ffdaf 100644
--- a/src/photos-help-overlay.ui
+++ b/src/photos-help-overlay.ui
@@ -37,6 +37,13 @@
                 <property name="accelerator">F1</property>
               </object>
             </child>
+            <child>
+              <object class="GtkShortcutsShortcut">
+                <property name="visible">1</property>
+                <property name="title" translatable="yes" context="shortcut window">Keyboard 
shortcuts</property>
+                <property name="accelerator">&lt;Primary&gt;question</property>
+              </object>
+            </child>
             <child>
               <object class="GtkShortcutsShortcut">
                 <property name="visible">1</property>