fix improper use of whitespace in README.md files

The use of the markdown trailing whitespace to indicate
line break should NOT be done when the following line is empty.

This removes such improper use of whitespace in README.md files.

2013/birken/README.md

@@ -2,7 +2,7 @@
 
 Michael Birken  
 <o__1@hotmail.com>  
-<http://www.meatfighter.com/>  
+<http://www.meatfighter.com/>
 
 
 ## To build:
@@ -14,7 +14,7 @@ make alt
 ## To run:
 
 To see why we recommend the alternate version instead of the original version,
-see the [original code](#original-code) section. 
+see the [original code](#original-code) section.
 
 ```sh
 ./birken.alt < 17_columns_wide_paint_by_numbers_file