If you could rephrase the "should you..." part, it would become "in case...". So it would be like in the rephrased example below.
It basically means "in the event of/that...":
In this section, we look at how the shuffle works, as a basic understanding would be helpful, in case you needed to optimize a Map-Reduce program.
See also this example taken from the NOAD:
Should anyone arrive late, admission is likely to be refused.
[In case/in the event that someone arrives late, admission is likely to be refused.]