message: Clarify title when importing a table
  The flow to import a table definition in Superset is confusing, user may
  think they are creating a table or what not. This makes the flow a bit
  more clear.
diff: @@ -156,7 +156,7 @@ class TableModelView(DatasourceModelView, DeleteMixin, YamlExportMixin): # noqa
  list_title = _('List Tables')
  show_title = _('Show Table')
  - add_title = _('Add Table')
  + add_title = _('Import a table definition')
  edit_title = _('Edit Table')
  list_columns = [
  