conflicting doc and README

In the generated `components.txt` :
```
# Whitespace is ignored. The package name cannot contain a - character or
# other special characters. The relative path should be the path to the
# folder containing the setup.py file for the package.
```

In the README.md, the example uses dashes :
```
For the simple case where your repository contains a single package that has its setup.py file in the root of your repository and works on python 2 and 3, you could add a line like:

project-identifier-without-spaces: ./
```

I *presume* the no dashes rule is relevant to the path names and not the actual pypi package names (many of which use dashes).