Looking for documentation on DB2 Version 10.5 for Linux, Unix and Windows that has been recently released (GAed on June 14, 2013), here is a Knowledge Collection for DB2 V10.5 that might help you get started.
DB2 Version 10.5 Activation key part numbers:
Download initial Version 10.5 clients and drivers
Evaluate: IBM DB2 with BLU Acceleration for Linux, UNIX and Windows
DB2 V10.5 Information Center:
New Enhancements in DB2 V10.5