docs: Update list widgets docs
Removed sentence that claimed the view will wrap the model in a GtkSingleSelection, as it's no longer true. Fixed the code example in GtkListView for the same reason. Fixed a small typo in GtkDropDown docs.
Removed sentence that claimed the view will wrap the model in a GtkSingleSelection, as it's no longer true. Fixed the code example in GtkListView for the same reason. Fixed a small typo in GtkDropDown docs.