docs: SC/21---Add new graphics introduced in Commit 9ad9383078faa (co…

…nt.)

These files were added for 0697c8c.  Why they weren't included
is unclear.

There was a repeat cycle to add in Makefile.am for its parent commit,
involving two "git reset HEAD^" commands.  The only possibility I can
think of is that I had not done the third renaming (prefix the sc21_,
remove in foreach for all .eps files needed for repeat "git mv", and
prepend again), before the second "git add".  However, I didn't have to
rename the new graphics file this morning.

Moral is to check the files before pushing... (as I'd done the first
time around).