Fix #1926852 [[Enhancement] Warn before removing news source from the Add custom news sources window](https://bugs.launchpad.net/calibre/+bug/1926852)

src/calibre/gui2/dialogs/custom_recipes.py

@@ -271,6 +271,7 @@ class RecipeList(QWidget):  # {{{
     def remove(self):
         idx = self.view.currentIndex()
         if idx.isValid():
+            if confirm_delete(_('Are you sure you want to permanently remove this recipe?'), 'remove-custom-recipe', parent=self):
                 self.model.remove((idx.row(),))
                 self.select_row()
                 if self.model.rowCount() == 0: