Literate: add 2nd include to match NuGet package layout

literate.fsx currently assumes the binaries to be in ../bin/.
However, when using literate directly from the NuGet package,
the binaries are actually in ../lib/net40/.
I've added a second include directive so it works in both situations
Merge pull request #29 from cdrnet/pr-literate-nuget-include

Literate: add 2nd include to match NuGet package layout