Java SDK Prepared Queries documentation is outdated

The documentation on running prepared N1QL queries using the Java SDK appear to be outdated. The documentation example is still using the `adhoc` flag on the N1qlQuery object. This flag no longer exists in the SDK. It appears that there are a number of Java classes that should be used instead. PreparedN1qlQuery, PrepareStatement, and PreparedPayload. The Java SDK documentation should be updated to reflect a correct way of using at least the minimum (simplest) use of these classes for running a prepared query.