yoda: fix missing rename icon in toolbar

edit-rename-symbolic isn't part of the COSMIC/Pop/Adwaita/WhiteSur-dark
icon sets, so the Rename button rendered empty. Swap to
document-edit-symbolic which is present in Adwaita (the standard fallback
in the freedesktop-icons resolution chain) and semantically fits edit/rename.

src/app.rs

@@ -6542,7 +6542,7 @@ impl Application for App {
             let toolbar = widget::row::with_children(vec![
                 tb_btn("folder-new-symbolic", fl!("new-folder"),
                        Action::NewFolder.message(None), true).into(),
-                tb_btn("edit-rename-symbolic", fl!("rename"),
+                tb_btn("document-edit-symbolic", fl!("rename"),
                        Action::Rename.message(None), true).into(),
                 tb_btn("edit-delete-symbolic", fl!("delete"),
                        Action::Delete.message(None), true).into(),