Update README.org

While updating the HiBC we also created some larger changes in the structure of the database. In short: The "GENOME", "rRNA_SPE_GEN" and "rRNA" tables were either merged with the "ISOLATE" table or deleted entirely. Additionally another function was added to the "ISOLATE" table. The new "FK_PUBLIC" column is linked to the "TRUE_FALSE" table and allows us to state, if an entry is supposed to be publicly available or not.

Because of this structural changes I had to change the description of the database tables in the README file