Format/typo check 1989/vanb/README.md

There were some places where there should not have been a \ at the end
of lines that were fixed. This occurred because there were spaces at the
end of the lines by accident. Very little else had to be done here.

1989/vanb/README.md

@@ -17,26 +17,26 @@ make all
 ## Try:
 
 ```sh
-./vanb the rug gary lent\
+./vanb the rug gary lent
 ./vanb unix is better than os/2
 ```
 
 ## Judges' remarks:
 
 This program computes all proper subsets of the set of
-arguments passed to it.  Each subset is printed with one\
+arguments passed to it.  Each subset is printed with one
 element on each line, followed by a line of ten dashes.
 
 
 
 ## Author's remarks:
 
-The program has the following charming and possibly\
+The program has the following charming and possibly
 non-portable features:
 
 * It has no local or global variables, only the command-line parameters.
 
-* It calls main recursively.
+* It calls `main()` recursively.
 
 * It alters the command-line parameters.