update fa21 student projects

[njr2128]

edit projects under fall 2021: https://cu-mkp.github.io/research-teaching-companion/resources/student-projects/

[ps2270]

I have checked all these and all links work.
Maybe @njr2128 wants to fix tables in https://cu-mkp.github.io/research-teaching-companion/resources/student-projects/fa21_lin+sundar_danli+anusha_final-project_regimens-remedies/
(https://github.com/cu-mkp/research-teaching-companion/blob/main/content/resources/student-projects/fa21_lin+sundar_danli+anusha_final-project_regimens-remedies.md)
Not absolutely necessary.

[ps2270]

@njr2128
Can you please fix the + problem in the following https://cu-mkp.github.io/research-teaching-companion/resources/student-projects/fa21_lin+sundar_danli+anusha_final-project_regimens-remedies/
The link does not work in teaching640.

[ps2270]

@njr2128
More + problems. The following do not link in teaching640:
https://cu-mkp.github.io/research-teaching-companion/resources/student-projects/fa21_atkins+joyce-farley_charlotte+siobhan_pranks/
https://cu-mkp.github.io/research-teaching-companion/resources/student-projects/fa21_zayas+waters_elliot+mac_final-project-soundscape/
https://teaching640.makingandknowing.org/resources/student-projects/sp22_bergen+sabet_jamie+sofia_final-project_grotto/

[ps2270]

@njr2128
I have fixed all these filenames and associated pdfs, xlsx, and docx filenames.
Media folders are still named with +, but until teaching640 has a new build, we won't be able to see if the images for these folders work.
Please do a new build at your earliest convenience and I will check this over.