Update year-specific comments

The challenges are no longer an exceptional thing, but are still
worth calling out. Ideally these should be config, but this will
do for now.

comp/league.html

@@ -14,10 +14,10 @@ <h1>League Status</h1>
 </p>
 
 <p>
-  For SR2023 teams can earn league points through a series of
-  <a href="https://studentrobotics.org/docs/resources/2023/rulebook.html#challenges">challenges</a>,
+  Teams can earn league points through a series of
+  <a href="https://studentrobotics.org/docs/resources/2024/rulebook.html#challenges">challenges</a>,
   from league matches at the
-  <a href="https://studentrobotics.org/events/sr2023/virtual-competition/">virtual competition</a>
+  <a href="https://studentrobotics.org/events/sr2024/virtual-competition/">virtual competition</a>
   and from the league matches at the in-person competition in April.
 </ul>