A developer needs to prepare the file README.

To prepare the file README.md in the working tree for the next commit operation in Git, the command git add README.md should be used. This command stages the file, meaning it adds the file's current content to the staging area, which is a preparatory step before committing it to the repository.

git add README.md: Adds the README.md file to the staging area.

git commit README.md: Commits all staged changes (not just README.md unless it is the only file staged).

References: Pro Git book by Scott Chacon and Ben Straub, Git documentation.