Fix headings

chapter1.md

@@ -1,5 +1,5 @@
-1. The DNS protocol
--------------------
+1 - The DNS protocol
+====================
 
 We'll start out by investigating the DNS protocol and use our knowledge thereof
 to implement a simple client.

chapter2.md

@@ -1,5 +1,5 @@
-2. Building a stub resolver
----------------------------
+2 - Building a stub resolver
+============================
 
 While it's slightly satisfying to know that we're able to succesfully parse DNS
 packets, it's not much use to just read them off disk. As our next step, we'll

chapter3.md

@@ -1,5 +1,5 @@
-3. Adding more Record Types
----------------------------
+3 - Adding more Record Types
+============================
 
 Let's use our program to do a lookup for ''yahoo.com''.
 

chapter4.md

@@ -1,5 +1,5 @@
-4. Baby's first DNS server
---------------------------
+4 - Baby's first DNS server
+===========================
 
 Haven gotten this far, we're ready to make our first attempt at writing an
 actual server. In reality, DNS servers fullfil two different purposes:

chapter5.md

@@ -1,5 +1,5 @@
-5. Recursive Resolve
---------------------
+5 - Recursive Resolve
+=====================
 
 Our server is working, but being reliant on another server to actually perform
 the lookup is annoying and less than useful. Now is a good time to dwelve into