Updated get-clean-data-proj README

- Added header section to specify HTML output and
  to keep the markdown file for viewing on GitHub
- Added a description of the data used in the project
- Added a description of the project
Updated get-clean-data-proj Codebook

- Added header to specify HTML output and to keep the
  markdown file for viewing on GitHub
- Added a data description
- Added a list of data files
- Added a diagram from David Hood showing the data file
  relationships
- Added a description of the project