Dave
Since the uTasker OS has been stable for about 11 years there has been no need to update its document.
Documentation updates are made on a regular basis for new features and parts support.
FreeRTOS is included in the package (that is it is set up to immediately run on [all supported] HW platforms) and allows the uTasker OS and its tasks to run in a FreeRTOS task so that existing (FreeRTOS based) projects can be used with the uTasker framework which delivers advanced drivers and protocols and such. This is mentioned on the start side in the feature list: https://www.utasker.com/index.html but otherwise is not used that often since users tend to switch to the uTasker OS because it reduces RAM usage and tends to be faster in operation for most general purpose embedded projects.
Since, when RUN_IN_FREE_RTOS is enabled, the framework gives an operational FreeRTOS project (whereby HW and startup is managed by uTasker) FreeRTOS users can work in their normal way and just need to decide which drivers and stacks etc. they actually want to use from the uTasker part (running as a low priority FreeRTOS task).
uTasker focuses on HW support, drivers and protocol stacks and not on the OS.
Regards
Mark