fix 4 lines with trailing whitespaces - 1984/mullender/README.md

In one case, a <br /> is used to break a line.

in the other 3 cases, where a line break was
not needed, trailing whitespace were removed.

1984/mullender/README.md

@@ -1,6 +1,6 @@
 # The Grand Prize
 
-Sjoerd Mullender  
+Sjoerd Mullender<br />
 <https://github.com/sjoerdmullender>
 
 Robbert van Renesse