What is a good clock source for the designs? Will the wishbone clock be reliable?

wb clock is same as system clock, I'm using it for my designs

@Matt Venn will the system clock be 10 MHz? Can't find any definite answers.

this is all I know: https://skywater-pdk.slack.com/archives/C017HPHCMEY/p1606154089087800

Then I would target 10 MHz for my design and UART controller