replace trailing whitespace with blackslash in README.md

As an alternative to the markdown trailing whitespace as a line
break, we use a trailing blackslash as a markdown line break.

2019/burton/README.md

@@ -30,7 +30,7 @@ unix utilities available as winning entries.
 
 ### Synopsis:
 
-Feed it anything on stdin.   
+Feed it anything on stdin.\
 The output should look familiar.
 
 Compiles cleanly with:
@@ -62,13 +62,13 @@ This program follows FreeBSD and macOS, the arbiters of correct for these purpos
 
 ### Limits:
 
-Requires the C locale and ASCII character set.   
+Requires the C locale and ASCII character set.\
 Input should be less than ten million octets "toavoidthisproblem".
 
 ### See Also:
 
-You can enjoy this code from beginning to end.   
-No whitespace was harmed in the creation of this program.   
+You can enjoy this code from beginning to end.\
+No whitespace was harmed in the creation of this program.\
 All your base belong to us, but the constants seem a bit ... off?
 
 ### Bonus