Fixeed pr-uc-basic figure

We had a mixture of tabs and spaces in left margin of the figure.
Changed to just spaces.
Expand capabiliites exchange section

Added examples for exchange of mixed capabilities. Fixed some
formatting in figures. Removed content from mixed-cap use case section,
since I think it’s covered in the cap exchange section. Various
editorial edits.
Removed rendered text file

Better to render on demand than to try to keep this up to date.
Merge branch 'ben-work-in-progress'