Typo in Mapper.add_property docs

[Former user]

Add an indiviual MapperProperty to this mapper.

Should be

Add an individual MapperProperty to this mapper.

As seen in: http://www.sqlalchemy.org/docs/04/sqlalchemy_orm_mapper.html#docstrings_sqlalchemy.orm.mapper_Mapper http://www.sqlalchemy.org/docs/03/sqlalchemy_orm_mapper.html#docstrings_sqlalchemy.orm.mapper_Mapper

[jek]

b0991bf661964b3d1cafc4cf0ae4649e14f9b5ea. thanks!