Readme explaination

[ugintl]

I saw this in the project description "The composer create-project command passes ownership of all files to the project that is created. You should create a new git repository, and commit all files not excluded by the .gitignore file."

How to do it?

[7o7o]

If i'm not mistaken, you have to remove the .git folder in the root of your project and then create a new git repository with this commands:
git init .
git add -A
git commit -m "My first commit"
...or any message you want to add to your first project commit.

Then you can push your project to github by doing:
git remote add origin git@github.com:ugintl/your_new_repository.git
git push origin master
...replace your_new_repository with the name of your repository on github. If github complains you might need to authenticate with ssh keys or by creating a temporary token for you on github.

Anyway, if you are just starting with the project this is not needed to test it. This is required if you want to version control all your changes that you do to the code. I recommend you to read about git and its basics commands to get the general idea of it. I hope this helps you.