xcbgen: Fix equation in documentation of `Alignment`.
@@ -1015,7 +1015,7 @@ impl NamedTypeRef {
/// An alignment specification.
///
/// This structure represents a requirement that some byte position `pos` satisfies
-/// `(pos + offset) % align == 0`.
+/// `pos % align == offset`.
///
/// `align` must be a power of 2 and `offset` must be less than `align`.
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
