fix links (alshedivat#2278)

This PR fixes/updates broken/outdated links on the `README.md`

README.md

@@ -152,11 +152,11 @@ Feel free to add your own page(s) by sending a PR.
 <td>Courses</td>
 <td>
 CMU PGM (<a href="https://sailinglab.github.io/pgm-spring-2019/" target="_blank">S-19</a>) <br>
-CMU DeepRL (<a href="https://cmudeeprl.github.io/703website_f19/" target="_blank">F-19</a>, <a href="https://cmudeeprl.github.io/Spring202010403website/" target="_blank">S-20</a>, <a href="https://cmudeeprl.github.io/703website/" target="_blank">F-20</a>, <a href="https://cmudeeprl.github.io/403_website/" target="_blank">S-21</a>, <a href="https://cmudeeprl.github.io/703website_f21/" target="_blank">F-21</a>, <a href="https://cmudeeprl.github.io/403website_s22/" target="_blank">S-22</a>) <br>
+CMU DeepRL (<a href="https://cmudeeprl.github.io/403_website/" target="_blank">S-21</a>, <a href="https://cmudeeprl.github.io/703website_f21/" target="_blank">F-21</a>, <a href="https://cmudeeprl.github.io/403website_s22/" target="_blank">S-22</a>, <a href="https://cmudeeprl.github.io/703website_f22/" target="_blank">F-22</a>, <a href="https://cmudeeprl.github.io/403website_s23/" target="_blank">S-23</a>, <a href="https://cmudeeprl.github.io/703website_f23/" target="_blank">F-23</a>) <br>
 CMU MMML (<a href="https://cmu-multicomp-lab.github.io/mmml-course/fall2020/" target="_blank">F-20</a>, <a href="https://cmu-multicomp-lab.github.io/mmml-course/fall2022/" target="_blank">F-22</a>) <br>
 CMU AMMML (<a href="https://cmu-multicomp-lab.github.io/adv-mmml-course/spring2022/" target="_blank">S-22</a>, <a href="https://cmu-multicomp-lab.github.io/adv-mmml-course/spring2023/" target="_blank">S-23</a>) <br>
 CMU ASI (<a href="https://cmu-multicomp-lab.github.io/asi-course/spring2023/" target="_blank">S-23</a>) <br>
-CMU Distributed Systems (<a href="https://andrew.cmu.edu/course/15-440/" target="_blank">S-21</a>)
+CMU Distributed Systems (<a href="https://andrew.cmu.edu/course/15-440/" target="_blank">S-24</a>)
 </td>
 </tr>
 <tr>