Where are details regarding peripheral configuration for STM32 controllers in datasheets?
To get the detailed info including register map and other register details for an ST microcontroller, you want what they call the reference manual, not the datasheet or the user manual.

See for example:


Reference manual for STM32F405/415, STM32F407/417, STM32F427/437 and
STM32F429/439 lines
Reference manual for STM32F0x1/STM32F0x2/STM32F0x8  lines
Reference manual for STM32F401xB/C and STM32F401xD/E lines
Reference manual for STM32F100xx line