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.

1993/plummer/README.md

@@ -7,6 +7,7 @@ make all
 There is an [alternate version](#alternate-code) that lets you slow down the
 output of the program for modern systems.
 
+
 ## To use:
 
 ```sh
@@ -19,7 +20,6 @@ where:
 - arg is any argument
 
 
-
 ### Try:
 
 ```sh
@@ -36,7 +36,6 @@ via `usleep(3)`, defaulting at 200.
 
 ### Alternate build:
 
-
 ```sh
 make alt
 ```
@@ -50,7 +49,6 @@ make clobber SLEEP=50 alt
 
 ### Alternate use:
 
-
 Use `plummer.alt` as you would `plummer`.