Make Wikipedia link for Xerox Alto clickable.

Author: youngman-g

cpu/src/control.rs

@@ -88,7 +88,7 @@ pub(crate) enum ProgramCounterChange {
 /// The Lincoln Laboratory book "MIT Lincoln Laboratory: Technology in
 /// Support of National Security" states (on page 462) that The Xerox
 /// Alto also used sequences for I/O.  See also
-/// https://en.wikipedia.org/wiki/Xerox_Alto#Architecture
+/// <https://en.wikipedia.org/wiki/Xerox_Alto#Architecture>
 #[derive(Debug)]
 struct SequenceFlags {
     flag_values: u64,