doc: update install docs for Windows and Go 1, add golang-announce to /project

R=golang-dev, bradfitz, r, rsc
CC=golang-dev
https://golang.org/cl/5758044

doc/contrib.html

@@ -17,6 +17,15 @@ Go is an open source project developed by a team at
 Go is distributed under a <a href="/LICENSE">BSD-style license</a>.
 </p>
 
+<h3 id="announce"><a href="http://groups.google.com/group/golang-announce">Announcements Mailing List</a></h3>
+<p>
+A low traffic mailing list for important announcements, such as new releases.
+</p>
+<p>
+We encourage all Go users to subscribe to
+<a href="http://groups.google.com/group/golang-announce">golang-announce</a>.
+</p>
+
 <h2 id="resources">Developer Resources</h2>
 
 <h3 id="source"><a href="https://code.google.com/p/go/source">Source Code</a></h3>

doc/install.html

@@ -114,7 +114,14 @@ Terminal sessions for the change to take effect.
 <h3 id="windows">Windows</h3>
 
 <p>
-<font color="red">TODO: windows installation instructions.</font>
+Open the <code>.msi</code> file and follow the prompts to install the Go tools.
+By default, the installer puts the Go distribution in <code>c:\Go</code>.
+</p>
+
+<p>
+The installer should put the <code>c:\Go\bin</code> directory in your
+<code>PATH</code> environment variable. You may need to restart any open
+command prompts for the change to take effect.
 </p>
 
 <h2 id="testing">Testing your installation</h2>
@@ -173,8 +180,13 @@ idiomatic Go code.
 </p>
 
 <p>
-For the full story, consult Go's extensive 
-<a href="/doc/">documentation</a>.
+For the full story, consult Go's extensive <a href="/doc/">documentation</a>.
+</p>
+
+<p>
+Subscribe to the
+<a href="http://groups.google.com/group/golang-announce">golang-announce</a>
+mailing list to be notified when a new stable version of Go is released.
 </p>