I found it to have quite a lot of useful pointers. Specifically –https://static.docs.arm.com/swog309707/a/Arm_Neoverse_N1_Sof...

https://static.docs.arm.com/ddi0487/ea/DDI0487E_a_armv8_arm....

- these two docs gives lot of useful information.

And the repo itself contain a number of examples (like ffmpeg) that have been optimized based on these manuals.