Folders on a public repository's page could not be opened, so anyone given the link saw only the top-level files. Each folder now opens a page listing what is in it, and each file opens a page showing its text, with Markdown files shown as a document. Every folder and file has its own address to share, and the names above it lead back up to the repository.
Open as plain text beside a file's name shows the file as plain text, as selecting a file name did before.