Re: [PATCH v7] doc: add an explanation of Git's data model

> +2. The *file type*, which must be one of these five types:
> +  - *regular file*
> +  - *executable file*
> +  - *symbolic link*
> +  - *directory*
> +  - *gitlink* (for use with submodules)
> +3. The <<object-id,*object ID*>> with the contents of the file, directory,
> +   or gitlink.
> ++
> +For example, this is how a tree containing one directory (`src`) and one file
> +(`README.md`) is stored:
> ++
> +----
> +100644 blob 8728a858d9d21a8c78488c8b4e70e531b659141f README.md
> +040000 tree 89b1d2e0495f66d6929f4ff76ff1bb07fc41947d src
> +----
> +
> +NOTE: In the output above, Git displays the file type of each tree entry
> +using a format that's loosely modelled on Unix file modes (`100644` is
> +"regular file", `100755` is "executable file", `120000` is "symbolic
> +link", `040000` is "directory", and `160000` is "gitlink"). It also
> +displays the object's type: `blob` for files and symlinks, `tree` for
> +directories, and `commit` for gitlinks.