readme review

[zongqi-wang]

Hello!
I like the amount of information given in the read me. It is simple enough for someone like me who does not have a biology background to understand it completely. There are a couple things that I have questions about.

1. typo on last theme; it should be 3 instead of 4.
2. I don't quite understand how theme 1 works, particularly the designing of vaccines.
3. I would like to see the first part into more sections.

[zongqi-wang]

Congratulations on finishing Theme 1 and 2! I look forward to hearing from you tomorrow. I like your improved formatting. The only concern is to link your name and git repo, and maybe add some example pictures to help readers understand .