Update docs, fixes #40

Major overhaul of the README file, outdated docs have been removed.

Details (see CHANGELOG):
  * bring README up-to-date ([#44](https://github.com/tknerr/bills-kitchen/issues/44))
  * remove outdated GETTING_STARTED and COOKBOOK_DEVELOPMENT guides ([#40](https://github.com/tknerr/bills-kitchen/issues/40))
  * remove `W:\docs` with outdated doc materials and shortcuts