Fix typo: s/dataa/data/

[Robpol86]

Assuming "dataa" is a typo for "data".

[shimizukawa]

Thanks. The translation catalogs are automatically generated from the sphinx documentation. Now upstream file have been fixed. https://github.com/sphinx-doc/sphinx/commit/068f802df90ea790f89319094e407c4d5f6c26ff