add table with minimum GPU / VRAM requirements, compute times and performance averages

[ballerburg9005]

Crude example (not based on actual data):

rate	min. batch size	min. VRAM	dataset	training time	GPU
16Khz	64	10GB	20 h	3 days	RTX 3090
32Khz	64	50GB	100h	14 days	A100