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.

2018/mills/README.md

@@ -1,6 +1,6 @@
 # Best of show
 
-Christopher Mills <mrxo@sonic.net>  
+Christopher Mills <mrxo@sonic.net>
 
 ## To build:
 
@@ -212,7 +212,7 @@ you should see:
         Use, duplication or disclosure is subject to
         restrictions stated in Contract with Western
         Electric Company, Inc.
-        # 
+        #
 
 You are now running a single-user session of v6 UNIX.  You might want to start
 with `stty -lcase` because otherwise everything will be IN ALL CAPS.
@@ -382,7 +382,7 @@ Now `ls` will work, and we can try some other things while we are here:
         bi.s    
         @ a.out
         Hello, World!
-        @ 
+        @
 
 The last command is invoking the compiler for an extremely early version of
 the [B programming language] [3], the predecessor to C.  Thompson missed the