fix README.md 2015/endoh3

2015/endoh3/README.md

@@ -49,13 +49,14 @@ This program is a joke PDP-11 emulator.  ("ll-dpd" is embedded in the code.  Rea
 
 You got it?  This program is supposed to be used in this way:
 
-    $ wget http://ioccc.org/1984/mullender.c
-    $ clang -o prog prog.c mullender.c
-    $ ./prog
+```sh
+wget http://ioccc.org/1984/mullender.c
+clang -o prog prog.c mullender.c
+./prog
+```
 
 You can enjoy the legendary winner of the first IOCCC, again.
 
-
 ### Internal
 
 This program uses `__attribute__((constructor))`, which is a GCC extension, to hijack the main function call.  And then it interprets main as an instruction sequence.
@@ -77,7 +78,6 @@ It supports the minimal subset of instructions and addressing modes which are ne
   * 4: Autodecrement deferred
   * 6: Index (incomplete)
 
-
 ### Limitation
 
 Non-trivial combination of instruction and addressing mode may cause undefined behavior (unsequenced modification), such as attempting to autoincrement a destination register.  Index addressing mode works well only for R7 (PC register).