Restore trailing newline (engine issue tracked in QuantEcon/action-translation#116)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: mmcky

lectures/two_auctions.md

@@ -700,4 +700,4 @@ chi_squ_case.plot_winner_payment_distribution()
 3. Chandra Chekuri的算法博弈论讲义：https://chekuri.cs.illinois.edu/teaching/spring2008/Lectures/scribed/Notes20.pdf
 4. Tim Salmon的ECO 4400补充讲义：关于拍卖的一切：https://s2.smu.edu/tsalmon/auctions.pdf
 5. 拍卖理论-收益等价定理：https://michaellevet.wordpress.com/2015/07/06/auction-theory-revenue-equivalence-theorem/
-6. 顺序统计量：https://online.stat.psu.edu/stat415/book/export/html/834
+6. 顺序统计量：https://online.stat.psu.edu/stat415/book/export/html/834