fix urls

Author: rlanzafame

book/_config.yml

@@ -2,7 +2,7 @@
 # Learn more at https://jupyterbook.org/customize/config.html
 
 title: Python for Civil Engineers
-author: TU Delft Teachers and TAs, built with <a href="https://teachbooks.tudelft.nl/">TeachBooks</a> and <a href="https://jupyterbook.org/">Jupyter Book</a>, <a href="https://creativecommons.org/licenses/by/4.0/" target="_blank" rel="license noopener noreferrer"">CC BY 4.0<img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;" src="https://mirrors.creativecommons.org/presskit/icons/cc.svg" alt=""><img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;" src="https://mirrors.creativecommons.org/presskit/icons/by.svg" alt=""></a>
+author: TU Delft Teachers and TAs, built with <a href="https://teachbooks.io/">TeachBooks</a> and <a href="https://jupyterbook.org/">Jupyter Book</a>, <a href="https://creativecommons.org/licenses/by/4.0/" target="_blank" rel="license noopener noreferrer"">CC BY 4.0<img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;" src="https://mirrors.creativecommons.org/presskit/icons/cc.svg" alt=""><img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;" src="https://mirrors.creativecommons.org/presskit/icons/by.svg" alt=""></a>
 logo: figures/learn-python-logo-TUD-tight.png
 
 # Force re-execution of notebooks on each build.