Move procedure to separate file. Fixes #8
Use - for data files
Update blackout data procedure and rename two files
Small corrections
Use underscore in section field names
Add link to last data file

Note, in last commit, absolute links were changed to relative ones, and
the formatting in step 3 was fixed.
Underscore in field names

Follow up of 40cf6e1ca92342135693908a6327402bfb1877e1
Rename procedure files to README

Will render on GitHub -> Higher chance that people read this
Describe first SQL steps in combining the data
Add SQL for percentages
Small corrections
Set percentages to 0 for null
Merge tables SQL
Add combined data
Update all_sections to section_all
Pull in master