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.

1991/fine/README.md

@@ -32,7 +32,7 @@ rotated from `the rug gary lent`!
 
 ## Judges' remarks:
 
-This filter, 80 chars plus a newline, fits into a single line on most 
+This filter, 80 chars plus a newline, fits into a single line on most\
 terminals (unless your terminal has a line wrap mis-feature :-)).
 
 Note in 2023: fixing this entry to work with modern systems increased the size,
@@ -40,11 +40,11 @@ originally to 106 characters but dropped down to 85 with clever use of the
 Makefile and removal of a cast that was not strictly necessary.
 
 This entry is likely one of the smallest C implementations of this
-filter, excluding programs that resort to command line or include 
+filter, excluding programs that resort to command line or include\
 file tricks.
 
 How does this program work?  Which 3 bytes of C code can be changed
-into 2 bytes, allowing the program to still work, but also stripping 
+into 2 bytes, allowing the program to still work, but also stripping\
 the high bit off some input?
 
 ## Author's remarks: