Add mnemonics for donate and about

Author: AlexanderVanhee

data/ui/image_sidebar.blp

@@ -268,12 +268,12 @@ menu app_menu {
     }
 
     item {
-      label: _("Donate to Gradia 💙");
+      label: _("D_onate to Gradia 💙");
       action: "win.donate";
     }
 
     item {
-      label: _("About Gradia");
+      label: _("_About Gradia");
       action: "win.about";
     }
   }

data/ui/welcome_page.blp

@@ -101,12 +101,12 @@ menu app_menu {
     }
 
     item {
-      label: _("Donate to Gradia 💙");
+      label: _("_D_onate to Gradia 💙");
       action: "win.donate";
     }
 
     item {
-      label: _("About Gradia");
+      label: _("_About Gradia");
       action: "win.about";
     }
   }