hackage-repo-tool README seems incorrect

README of hackage-repo-tool said
> Create a directory ~/my-secure-repo containing a single subdirectory ~/my-secure-repo/package. Put whatever packages you want to make available from your repo in this subdirectory. At this point your repository might look like

I think that `~/my-secure-repo/index` rather than `~/my-secure-repo/package` is correct.
When I created `~/my-secure-repo/package`, the following error occured
> my-secure-repo/index: getDirectoryContents:openDirStream: does not exist (No such file or directory)

Also, I put `01-index.tar` file obtained by
```shell
curl -o 01-index.tar.gz https://hackage.haskell.org/01-index.tar.gz
gunzip 01-index.tar.gz
```
into `~/my-secure-repo`, as it said `~/my-secure-repo/01-index.tar: openBinaryFile: does not exist (No such file or directory)`

However, when I ran `hackage-repo-tool bootstrap --repo my-secure-repo --keys my-private-keys`, the same error message showed up and `01-index.tar` disappeared.

Did I do something wrong?