Reorganize README to make it more clear.

This also adds a note about required memory usage and instructions for
building from Git.

Author: metajack

README.md

@@ -3,18 +3,72 @@
 This is a compiler for Rust, including standard libraries, tools and
 documentation.
 
+## Quick Start
 
-## Installation
+### Windows
 
-The Rust compiler currently must be built from a [tarball], unless you
-are on Windows, in which case using the [installer][win-exe] is
-recommended.
+1. Download and use the [installer][win-exe].
+2. Read the [tutorial].
+2. Enjoy!
 
-Since the Rust compiler is written in Rust, it must be built by
-a precompiled "snapshot" version of itself (made in an earlier state
-of development). As such, source builds require a connection to
-the Internet, to fetch snapshots, and an OS that can execute the
-available snapshot binaries.
+> ***Note:*** Windows users should read the detailed
+> [getting started][wiki-start] notes on the wiki. Even when using
+> the binary installer the Windows build requires a MinGW installation,
+> the precise details of which are not discussed here.
+
+[tutorial]: http://static.rust-lang.org/doc/tutorial.html
+[wiki-start]: https://github.com/mozilla/rust/wiki/Note-getting-started-developing-Rust
+[win-exe]: http://static.rust-lang.org/dist/rust-0.7-install.exe
+
+### Linux / OS X
+
+1. Install the prerequisites (if not already installed)
+    * g++ 4.4 or clang++ 3.x
+    * python 2.6 or later (but not 3.x)
+    * perl 5.0 or later
+    * gnu make 3.81 or later
+    * curl
+2. Download and build Rust
+    You can either download a [tarball] or build directly from the [repo].
+    
+    To build from the [tarball] do:
+    
+        $ curl -O http://static.rust-lang.org/dist/rust-0.7.tar.gz
+        $ tar -xzf rust-0.7.tar.gz
+        $ cd rust-0.7
+    
+    Or to build from the [repo] do:
+
+        $ git clone https://github.com/mozilla/rust.git
+        $ cd rust
+
+    Now that you have Rust's source code, you can configure and build it:
+    
+        $ ./configure
+        $ make && make install
+    
+    You may need to use `sudo make install` if you do not normally have
+    permission to modify the destination directory. The install locations can
+    be adjusted by passing a `--prefix` argument to `configure`. Various other
+    options are also supported, pass `--help` for more information on them.
+
+    When complete, `make install` will place several programs into
+    `/usr/local/bin`: `rustc`, the Rust compiler; `rustdoc`, the
+    API-documentation tool, and `rustpkg`, the Rust package manager and build
+    system.
+3. Read the [tutorial].
+4. Enjoy!
+
+[repo]: https://github.com/mozilla/rust
+[tarball]: http://static.rust-lang.org/dist/rust-0.7.tar.gz
+[tutorial]: http://static.rust-lang.org/doc/tutorial.html
+
+## Notes
+
+Since the Rust compiler is written in Rust, it must be built by a
+precompiled "snapshot" version of itself (made in an earlier state of
+development). As such, source builds require a connection to the Internet, to
+fetch snapshots, and an OS that can execute the available snapshot binaries.
 
 Snapshot binaries are currently built and tested on several platforms:
 
@@ -25,42 +79,12 @@ Snapshot binaries are currently built and tested on several platforms:
 You may find that other platforms work, but these are our "tier 1"
 supported build environments that are most likely to work.
 
-> ***Note:*** Windows users should read the detailed
-> [getting started][wiki-start] notes on the wiki. Even when using
-> the binary installer the Windows build requires a MinGW installation,
-> the precise details of which are not discussed here.
-
-To build from source you will also need the following prerequisite
-packages:
-
-* g++ 4.4 or clang++ 3.x
-* python 2.6 or later (but not 3.x)
-* perl 5.0 or later
-* gnu make 3.81 or later
-* curl
-
-Assuming you're on a relatively modern *nix system and have met the
-prerequisites, something along these lines should work.
-
-    $ curl -O http://static.rust-lang.org/dist/rust-0.7.tar.gz
-    $ tar -xzf rust-0.7.tar.gz
-    $ cd rust-0.7
-    $ ./configure
-    $ make && make install
+Rust currently needs about 1.8G of RAM to build without swapping; if it hits
+swap, it will take a very long time to build.
 
-You may need to use `sudo make install` if you do not normally have
-permission to modify the destination directory. The install locations
-can be adjusted by passing a `--prefix` argument to
-`configure`. Various other options are also supported, pass `--help`
-for more information on them.
+There is lots more documentation in the [wiki].
 
-When complete, `make install` will place several programs into
-`/usr/local/bin`: `rustc`, the Rust compiler; `rustdoc`, the
-API-documentation tool, and `rustpkg`, the Rust package manager and build system.
-
-[wiki-start]: https://github.com/mozilla/rust/wiki/Note-getting-started-developing-Rust
-[tarball]: http://static.rust-lang.org/dist/rust-0.7.tar.gz
-[win-exe]: http://static.rust-lang.org/dist/rust-0.7-install.exe
+[wiki]: https://github.com/mozilla/rust/wiki
 
 
 ## License
@@ -71,8 +95,3 @@ BSD-like licenses.
 
 See LICENSE-APACHE, LICENSE-MIT, and COPYRIGHT for details.
 
-## More help
-
-The [tutorial] is a good starting point.
-
-[tutorial]: http://static.rust-lang.org/doc/tutorial.html