[gnome-builder] editor: switch to list-add

[Christian Hergert <chergert src gnome org>]

commit 2d5a96fe2ede0b1c76273abddb7f543174527b56
Author: Christian Hergert <chergert redhat com>
Date:   Mon Nov 29 15:29:41 2021 -0800

    editor: switch to list-add
    
    With the changes to document-open icon, list-add makes more sense.
    
    Fixes #1573

 src/plugins/editor/gbp-editor-workspace-addin.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/plugins/editor/gbp-editor-workspace-addin.c b/src/plugins/editor/gbp-editor-workspace-addin.c
index 6ff2ebb18..af81761c4 100644
--- a/src/plugins/editor/gbp-editor-workspace-addin.c
+++ b/src/plugins/editor/gbp-editor-workspace-addin.c
@@ -146,7 +146,7 @@ add_buttons (GbpEditorWorkspaceAddin *self,
   g_assert (IDE_IS_HEADER_BAR (header));
 
   self->new_button = g_object_new (DZL_TYPE_MENU_BUTTON,
-                                   "icon-name", "document-open-symbolic",
+                                   "icon-name", "list-add-symbolic",
                                    "focus-on-click", FALSE,
                                    "show-arrow", TRUE,
                                    "show-icons", FALSE,