tutorial: Restructure intro materials

Author: brson

doc/tutorial.md

@@ -6,18 +6,11 @@
 
 This is a tutorial for the Rust programming language. It assumes the
 reader is familiar with the basic concepts of programming, and has
-programmed in one or more other languages before. The tutorial covers
+programmed in one or more other languages before. It will often make
+comparisons to other languages in the C family. The tutorial covers
 the whole language, though not with the depth and precision of the
 [language reference](rust.html).
 
-## Disclaimer
-
-Rust is a language under development. The general flavor of the
-language has settled, but details will continue to change as it is
-further refined. Nothing in this tutorial is final, and though we try
-to keep it updated, it is possible that the text occasionally does not
-reflect the actual state of the language.
-
 ## First Impressions
 
 Though syntax is something you get used to, an initial encounter with
@@ -58,6 +51,14 @@ fragments of programs that don't compile on their own. To try them
 out, you might have to wrap them in `fn main() { ... }`, and make sure
 they don't contain references to things that aren't actually defined.
 
+## Disclaimer
+
+Rust is a language under development. The general flavor of the
+language has settled, but details will continue to change as it is
+further refined. Nothing in this tutorial is final, and though we try
+to keep it updated, it is possible that the text occasionally does not
+reflect the actual state of the language.
+
 # Getting started
 
 ## Installation