update index templates for citation and additional contributors

[oharac]

see nceas-learning-hub/2026_delta_week1#23

nceas-learning-hub/2026_delta_week1#23 (comment)

[oharac]

done! Trailing matter of index now includes:

This work is licensed under a [Creative Commons Attribution 4.0 International License](http://creativecommons.org/licenses/by/4.0/){.external target="_blank"}.

**Citation:** COURSE INSTRUCTORS (COURSE DATE), NCEAS coreR for Delta Science Program, COURSE DATE, NCEAS Learning Hub. [https://nceas-learning-hub.github.io/COURSE SITE](https://nceas-learning-hub.github.io/COURSE SITE/){.external target="_blank"}.

**Content contributors:** Ben Bolker, Amber E. Budden, Julien Brun, Angel Chen, Samantha Csik, Halina Do-Linh, Natasha Haycock-Chavez, S. Jeanette Clark, Julie Lowndes, Stephanie Hampton, Matt Jones, Samantha Katz, Nick J. Lyon, Erin McLean, Bryce Mecum, Casey O'Hara, Deanna Pennington, Karthik Ram, Jim Regetz, Tracy Teal, Camila Vargas Poulsen, Daphne Virlar-Knight, Leah Wasser.

This is a Quarto-built website. To learn more about Quarto sites visit [https://quarto.org/docs/websites/](https://quarto.org/docs/websites){.external target="_blank"}.