Readme update. The documentation specifically says that OR operations are not supported

Relevant url: https://developer.intuit.com/docs/0025_quickbooksapi/0050_data_services/020_key_concepts/00300_query_operations/0500_simplified_syntax

"The WhereClause filters the returned data according to the value of a property.

Note: Multiple clauses (filters) are AND'd.  The OR operation is not supported."
Merge pull request #95 from markrickert/readme-or-and

Readme update. The documentation specifically says that OR operations are not supported