add read.C file

[Shuyang19]

Shuyang created a new directory read_roots and there is a read.C file in it

[ddiaz006]

@Shuyang19 you have some merge errors. please fix these, then I can merge this PR.
do

git fetch upstream
git checkout main
git merge upstream/main

Then if the message says there are merge errors, you will need to edit the files then git add them again once you fixed the error