Fix tmp/format-headers.sh, format headers

The script had "s surrounding the git ls-files command which turned it
to a single file which of course is wrong.

Ran script again fixing many README.md files that had incorrect number
of blank lines for critical headers.

This will have to be done a final but a good number of files have been
corrected.

2004/gavin/README.md

@@ -90,6 +90,7 @@ you can use it with `QEMU`.
 make alt
 ```
 
+
 ### Alternate use:
 
 The use is mostly the same as `gavin` except that one initially executes `gavin.alt`