sys/xen/interface/io/blkif.h:
o Insert space in "Red Hat".
o Fix typo "discard-aligment" -> "discard-alignment"
o Fix typo "unamp" -> "unmap"
o Fix typo "formated" -> "formatted"
o Clarify the text for "params".
o Clarify the text for "sector-size".
o Clarify the text for "max-requests" in the backend section.