remove mention of afero from readme

as this is no longer being used

README.md

@@ -11,7 +11,6 @@ Nothing fancy about the code, all the heavy lifting is done by:
 * [go-jsonschema-generator](https://github.com/karuppiah7890/go-jsonschema-generator) - for generating JSON schema. It's a fork of [this](https://github.com/mcuadros/go-jsonschema-generator). Thanks to [@mcuadros](https://github.com/mcuadros)
 * [go-yaml](https://github.com/go-yaml/yaml/) - for YAML parsing
 * [cobra](https://github.com/spf13/cobra) - for CLI stuff
-* [afero](https://github.com/spf13/afero) - for file reading
 * [The Go stdlib](https://golang.org/pkg/) - for everything else
 
 ## Install