Document Derby usage running on Java 8 JEP 161 Compact Profiles

Document that Derby can run even under constrained Java runtime as planned for Java 8 Compact Profiles 2 and 3 (not 1, the smallest runtime, since it has no JDBC). Cf work in DERBY-5955 which made Derby run gracefully even when some normal Java runtime packages are missing, notably JNDI and JMX.

That work introduced six new data sources which have reduced functionality compared with the corresponding ones for full Java SE, in that there is no JNDI support. The six new data sources are for the client driver:

Client/server data sources for use with Java 8 Compact Profile 2 and above:

BasicClientDataSource40 - Data source
BasicClientConnectionPoolDataSource40 - Connection pooling data source
BasicClientXADataSource40 - XA data source

Embedded data sources for use with Java 8 Compact Profile 2 and above:

BasicEmbeddedDataSource40 - Data source
BasicEmbeddedConnectionPoolSource40 - Connection pooling data source
BasicEmbeddedXASource40 - XA data source