Update 1987 winning entries' README.md files

Format and typo fixes.

1987/heckbert/README.md

@@ -5,8 +5,9 @@ Pixar
 
 ## To build:
 
-        make all
-
+```sh
+make all
+```
 
 On System V systems, we had to compile with `-Dindex=strchr`.
 To compile on a 16 bit machine, change 300000 to 30000.
@@ -15,35 +16,39 @@ To compile on a 16 bit machine, change 300000 to 30000.
 
 ## Try:
 
-	./heckbert 40 < heckbert.c > ph.c; make ph
-	./ph 21 < heckbert.c > bar.c; make bar
-	# or more generally fold some other file at a positive column:
-	./ph col < file
+```sh
+./heckbert 40 < heckbert.c > ph.c; make ph
+./ph 21 < heckbert.c > bar.c; make bar
+# or more generally fold some other file at a positive column:
+./ph col < file
+```
 
 Ask yourself what happens to `foo.md` if you try:
 
-	./ph 40 < README.md > foo.md
-
+```sh
+./ph 40 < README.md > foo.md
+```
 
 ## Judges' remarks:
 
 Folding at the wrong length may be equivalent to a "Spindle or Mutilate" operation. For example:
 
-	./heckbert 40 < heckbert.c > ph.c ; make ph ; ./ph 20 < heckbert.c > bar.c ; make bar
+```sh
+./heckbert 40 < heckbert.c > ph.c ; make ph ; ./ph 20 < heckbert.c > bar.c ; make bar
+```
 
 Try not to
 [Fold, Spindle or Mutilate](https://repository.library.brown.edu/studio/item/bdr:788264/PDF/)
 files. :-)
 
-
-## Author's remarks:
-
-No comments were provided by the author.
-
 The judges used this program to fold up very long lines which the
 BSD fold(1) was unable to process. This program has been added
 to the contest tool chest.
 
+## Author's remarks:
+
+No remarks were provided by the author.
+
 ## Copyright and CC BY-SA 4.0 License:
 
 This file is Copyright (c) 2023 by Landon Curt Noll.  All Rights Reserved.