[lib] using `parse_from_file` instead of `parse_file`

This method seems to be compatible with older versions of Pod::Text
[lib] removing duplicate pod in main lib

We are now reading from the README.pod which thus saves us some duplicated
work when updating version numbers etc and means that we only have to update
the content of one file as opposed to ensuring that both the module and the
README contain the same (pod) information.