Add virtual pointer to location

Not possible to give them the Zoom link until they register, so this is just a meek attempt to keep potential virtual attendees from scanning the header and leaving disappointed

content/tutorial/_index.md

@@ -6,7 +6,7 @@ template="tutorial.html"
 *At [PLDI 2023][pldi-home] in Orlando*
 
 **When**: **Sunday June 18, 2023; morning session** <br/>
-**Where**: **Magnolia 9**
+**Where**: **Magnolia 9, with a virtual option (see below)**
 
 In the last four decades, the easiest way to improve performance of programs has been to simply wait; processor and process scaling took care of the rest.
 Sadly, Moore's law is over, there are no free lunches left, and everyone at the table is desperate.