change use of <br> with blackslash for markdown line breaks

1987/heckbert/README.md

@@ -1,6 +1,6 @@
 # Best Obfuscator of Programs
 
-Paul Heckbert<br>
+Paul Heckbert\
 
 ## To build:
 
@@ -45,9 +45,9 @@ Try not to
 [Fold, Spindle or Mutilate](https://repository.library.brown.edu/studio/item/bdr:788264/PDF/)
 files. :-)
 
-The judges used this program to fold up<br>
-very long lines which the BSD fold(1)<br>
-was unable to process. This program has<br>
+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: