addition to Shiro documentation

[Brian MacWhinney]

Dear Info-CHILDES,

  Martha Shiro asked me to add this additional clarificatory information
regarding her corpus of narratives from Venezuelan children:

The narratives in this data were collected from 113 Venezuelan children by
Martha Shiro of Universidad Central de Venezuela for a doctoral thesis under
the direction of Catherine Snow, Lowry Hemphill, and Victoria Purcell-Gates
of the Harvard Graduate School of Education.

--Brian MacWhinney