Create "getting started" guide for prototype 0.1

[knoepfel]

The getting-started guide should include enough information to allow users to:

1. Install Phlex using Spack
2. Create provider functions and register providers
3. Create algorithms and register them
   1. C++ algorithms
   2. Python algorithms
4. Create a program configuration that uses the layer_generator as the driver, and the providers and algorithms required
5. Execute the Phlex program using the program configuration in 4

[knoepfel]

This issue has been resolved with the installation guide in #204 and with the phlex-examples repository.