DOC: Documentation in the source code.

...n/java/org/caosdb/server/database/BackendTransaction.java

src/main/java/org/caosdb/server/jobs/Job.java

src/main/java/org/caosdb/server/jobs/JobAnnotation.java

src/main/java/org/caosdb/server/jobs/JobExecutionTime.java

src/main/java/org/caosdb/server/jobs/Schedule.java

src/main/java/org/caosdb/server/jobs/ScheduledJob.java

src/main/java/org/caosdb/server/transaction/Transaction.java

...a/org/caosdb/server/transaction/TransactionInterface.java

.../java/org/caosdb/server/transaction/WriteTransaction.java