fix some file extensions

Task/Knuth-shuffle/DWScript/knuth-shuffle.dw

@@ -0,0 +1,9 @@
+procedure KnuthShuffle(a : array of Integer);
+var
+   i, j, tmp : Integer;
+begin
+   for i:=a.High downto 1 do begin
+      j:=RandomInt(a.Length);
+      tmp:=a[i]; a[i]:=a[j]; a[j]:=tmp;
+   end;
+end;