[release-branch.go1.2] doc: document Go 1.2.1

Note the installation instructions change doesn't apply here,
so I had to patch this in manually instead of using release-apply.

R=minux.ma, r
CC=golang-codereviews, golang-dev
https://golang.org/cl/69860047

doc/devel/release.html

@@ -363,6 +363,12 @@ variable to build and install your own code and external libraries outside of
 the Go tree (and avoid writing Makefiles).
 </p>
 
+<h3 id="go1.2.minor">Minor revisions</h3>
+
+<p>
+go1.2.1 (released 2014/03/02) includes bug fixes to the <code>runtime</code>, <code>net</code>, and <code>database/sql</code> packages.
+See the <a href="https://code.google.com/p/go/source/list?name=release-branch.go1.2&r=7ada9e760ce34e78aee5b476c9621556d0fa5d31">change history</a> for details.
+</p>
 
 <h3 id="r58.minor">Minor revisions</h3>
 

doc/install.html

@@ -76,7 +76,7 @@ and extract it into <code>/usr/local</code>, creating a Go tree in
 </p>
 
 <pre>
-tar -C /usr/local -xzf go1.1.linux-amd64.tar.gz
+tar -C /usr/local -xzf go1.2.1.linux-amd64.tar.gz
 </pre>
 
 <p>