There are several PDF documents related to the r8 release.
Aspen R8 Release Notes lists the updates included in the release.
Aspen R8.1 and R8.2 release notes describe updates.
Aspen R8 quick start gives a general overview of how to configure an R8 system. It describes a multiple RIP installation.
Aspen troubleshooting R8 lists common questions or challenges and potential solutions.
Aspen CMYKS R8 describes how to configure this special case mode of the Aspen system. There is more CMYKS information here
Aspen v2 R8 quick start describes how to configure the Aspen v2 output plugin. It is necessary for stitching 2 engines together to create a 17" print area.
Aspen R8 Test environment Installation Instructions is only of interest to OEM engineers and support staff. It describes how to configure a stitched-press test system with no stitched 
printer connected.