kilobyte unit spelled "K bytes"

In the documentation there is a single instance of “K bytes” being used to
denote kilobytes (kB or kilobyte used everywhere else), which isn’t really
correct as the k should be lowercased.  The attached diff fixes this to make it
consistent with the rest of the documentation.  I opted for kilobytes rather
than kB to match the rest of the document in question.

cheers ./daniel