How to organize the work of the git in the internal folder of the project?

Question

git

There is a project on any framework (for example, laravel), it has its own structure, there is also a coder who does not understand anything about this, the question is how to organize such a thing using git:
2 users - a developer and a coder
The developer has full access to everything project
Developer only in MySuperApp/assets
The layout designer can only push inside assets, he does not see other folders and cannot edit
. assets, if necessary), the layout designer can only push and pull assets, so that I myself then collect everything with gulp (figuratively)
I don’t really understand the git, if you are too lazy to answer, tell me in which direction to google, this will already help)
Thank you in advance.

Answer 1

git submodule / subtree
https://habrahabr.ru/post/75964/