The lubuntu manual currently links to on downloading the image https://help.ubuntu.com/community/VerifyIsoHowto but this recommends sha256 while we lubuntu.me provides md5 sums having multiple different hash functions when first install just introduces new layers of complexity. A new user has a high likelyhood of never hearing of a cryptographic hash function and having mulitple different ones just makes things more complicated. Sure md5 is less computationally intesive but 1 we refocused 2 will take longer to grok md5 and sha256 both do the same thing vs cpu cycles. So both the website and manual will need to be updated.