doc: add prominent download button to getting started page

Also remove the introduction, which says what the rest of the
page says anyway.

Fixes golang#5182.

R=golang-dev, kamil.kisiel, r
CC=golang-dev
https://golang.org/cl/8281044

doc/install.html

@@ -3,25 +3,34 @@
 	"Path":  "/doc/install"
 }-->
 
-<h2 id="introduction">Introduction</h2>
+<h2 id="download">Download the Go distribution</h2>
 
 <p>
-Go is an open source project with a BSD-style license.
-There are two official Go compiler toolchains: the <code>gc</code> Go compiler
-and the <code>gccgo</code> compiler that is part of the GNU C Compiler (GCC).
+<a href="http://code.google.com/p/go/downloads" id="start" class="download" target="_blank">
+<span class="big">Download Go</span>
+<span class="desc">Click here to visit the downloads page</span>
+</a>
 </p>
 
 <p>
-The <code>gc</code> compiler is the more mature and well-tested of the two.
-This page is about installing a binary distribution of the <code>gc</code>
-compiler.
+Click the link above to visit the
+<a href="http://code.google.com/p/go/downloads">Go project's downloads page</a>
+and select the binary distribution that matches your operating system and
+processor architecture.
 </p>
 
 <p>
-For information about installing the <code>gc</code> compiler from source, see
-<a href="/doc/install/source">Installing Go from source</a>.
-For information about installing <code>gccgo</code>, see
-<a href="/doc/install/gccgo">Setting up and using gccgo</a>.
+Official binary distributions are available for the FreeBSD, Linux, Mac OS X
+(Snow Leopard, Lion, and Mountain Lion), NetBSD, and Windows operating systems
+and the 32-bit (<code>386</code>) and 64-bit (<code>amd64</code>) x86 processor
+architectures.
+</p>
+
+<p>
+If a binary distribution is not available for your combination of operating
+system and architecture you may want to try
+<a href="/doc/install/source">installing from source</a> or
+<a href="/doc/install/gccgo">installing gccgo instead of gc</a>.
 </p>
 
 <h2 id="requirements">System requirements</h2>
@@ -56,29 +65,6 @@ <h2 id="requirements">System requirements</h2>
 Downloads preferences panel.
 </p>
 
-<h2 id="download">Download the Go tools</h2>
-
-<p>
-Visit the
-<a href="http://code.google.com/p/go/downloads">Go project's downloads page</a>
-and select the binary distribution that matches
-your operating system and processor architecture.
-</p>
-
-<p>
-Official binary distributions are available
-for the FreeBSD, Linux, Mac OS X (Snow Leopard/Lion), NetBSD, and Windows operating systems
-and the 32-bit (<code>386</code>) and 64-bit (<code>amd64</code>)
-x86 processor architectures.
-</p>
-
-<p>
-If a binary distribution is not available for your
-OS/arch combination you may want to try
-<a href="/doc/install/source">installing from source</a> or
-<a href="/doc/install/gccgo">installing gccgo instead of gc</a>.
-</p>
-
 <h2 id="install">Install the Go tools</h2>
 
 <p>

doc/style.css

@@ -198,6 +198,9 @@ div#blog .read a {
 	border: 1px solid #375EAB;
 	background: #E0EBF5;
 }
+.download {
+	width: 150px;
+}
 
 div#menu {
 	float: right;