doc: link directly to https://golang.org/dl/

Fixes #8705.

LGTM=adg
R=golang-codereviews, bradfitz, adg
CC=golang-codereviews
https://golang.org/cl/142890044

doc/go1.html

@@ -2035,4 +2035,4 @@ They are available for many combinations of architecture and operating system
 Installation details are described on the
 <a href="/doc/install">Getting Started</a> page, while
 the distributions themselves are listed on the
-<a href="/dl/">downloads page</a>.
+<a href="https://golang.org/dl/">downloads page</a>.

doc/install.html

@@ -6,14 +6,14 @@
 <h2 id="download">Download the Go distribution</h2>
 
 <p>
-<a href="/dl/" id="start" class="download" target="_blank">
+<a href="https://golang.org/dl/" 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>
-<a href="https://code.google.com/p/go/wiki/Downloads?tm=2" target="_blank">Official binary
+<a href="https://golang.org/dl/" target="_blank">Official binary
 distributions</a> are available for the FreeBSD (release 8 and above), Linux, Mac OS X (Snow Leopard
 and above), and Windows operating systems and the 32-bit (<code>386</code>) and
 64-bit (<code>amd64</code>) x86 processor architectures.
@@ -70,7 +70,7 @@ first <a href="#uninstall">remove the existing version</a>.
 <h3 id="tarball">Linux, Mac OS X, and FreeBSD tarballs</h3>
 
 <p>
-<a href="https://code.google.com/p/go/wiki/Downloads?tm=2">Download the archive</a>
+<a href="https://golang.org/dl/">Download the archive</a>
 and extract it into <code>/usr/local</code>, creating a Go tree in
 <code>/usr/local/go</code>. For example:
 </p>
@@ -127,7 +127,7 @@ location.
 <h3 id="osx">Mac OS X package installer</h3>
 
 <p>
-<a href="https://code.google.com/p/go/wiki/Downloads?tm=2">Download the package file</a>,
+<a href="https://golang.org/dl/">Download the package file</a>,
 open it, and follow the prompts to install the Go tools.
 The package installs the Go distribution to <code>/usr/local/go</code>.
 </p>
@@ -150,7 +150,7 @@ MSI installer that configures your installation automatically.
 <h4 id="windows_msi">MSI installer</h4>
 
 <p>
-Open the <a href="https://code.google.com/p/go/wiki/Downloads?tm=2">MSI file</a>
+Open the <a href="https://golang.org/dl/">MSI file</a>
 and follow the prompts to install the Go tools.
 By default, the installer puts the Go distribution in <code>c:\Go</code>.
 </p>
@@ -164,7 +164,7 @@ command prompts for the change to take effect.
 <h4 id="windows_zip">Zip archive</h4>
 
 <p>
-<a href="https://code.google.com/p/go/wiki/Downloads?tm=2">Download the zip file</a> and extract it into the directory of your choice (we suggest <code>c:\Go</code>).
+<a href="https://golang.org/dl/">Download the zip file</a> and extract it into the directory of your choice (we suggest <code>c:\Go</code>).
 </p>
 
 <p>
@@ -270,5 +270,3 @@ The official mailing list for discussion of the Go language is
 Report bugs using the
 <a href="//golang.org/issue">Go issue tracker</a>.
 </p>
-
-