~comp/index: remove rules under headlines

comp/index.md

 >Topics focused on the more technical side of computers, things of interest to programmers, sysadmins, etc.
 
 ## Notable Topics
----
 
   * [What operating system do you use?](https://tildes.net/~comp/3t3)
   * [Linux distro of choice?](https://tildes.net/~comp/2dh)
@@ -10,7 +9,7 @@
   * [What do you think every programmer should know to do?](https://tild.es/amx)
 
 ## Where to start
----
+
 Here is a list of places to get started with different programming languages/concepts
 
   * [Web development - freeCodeCamp](https://freecodecamp.com)
@@ -22,7 +21,6 @@ Here is a list of places to get started with different programming languages/con
 
 
 ## Programming Challenges
----
 
   * [Translate 24-hour time into words](https://tildes.net/~comp/we)
   * [Undo this "Caesar" cipher](https://tildes.net/~comp/ze)