fix README.md for 2004/arachnid

2004/arachnid/README.md

@@ -8,17 +8,23 @@
 
     http://www.notdot.net/
 
-## To build:
+# To build:
 
-        make all
+```sh
+make
+```
 
-### To run
+### To run:
 
+```sh
 ./arachnid [mazefile]
+```
 
 ### Try:
 
+```sh
 ./arachnid arachnid.info
+```
 
 ## Judges' comments
 
@@ -49,7 +55,9 @@
 for the particularaly insane maze explorers out there.
 
 Usage:
+
+```sh
 ./arachnid [mazefile]
+```
 
 You can explore the maze using the w,a,s, and d keys.
-