List main feature commands in README

[peterblazejewicz]

I've found it hard to find out available features of pecan-waffle module - list of cmdlets that actually are core features of module, one directly related to Project and Item (Show-Templates, Add-Project, etc) The good source of these core cmdlets is test script btw. I think this is crucial to help people play with this module.

[sayedihashimi]

Thanks Peter I'll also update to only export user facing functions. In the mean while the sample files at https://github.com/ligershark/pecan-waffle/tree/master/templates should be helpful.