doc: document Go 1.2.1

LGTM=minux.ma
R=golang-codereviews, minux.ma
CC=golang-codereviews
https://golang.org/cl/69970047
diff --git a/doc/install.html b/doc/install.html
index b02324b..c44efc4 100644
--- a/doc/install.html
+++ b/doc/install.html
@@ -81,8 +81,8 @@
 
 <p>
 Choose the archive file appropriate for your installation.
-For instance, if you are installing Go version 1.2 for 64-bit x86 on Linux,
-the archive you want is called <code>go1.2.linux-amd64.tar.gz</code>.
+For instance, if you are installing Go version 1.2.1 for 64-bit x86 on Linux,
+the archive you want is called <code>go1.2.1.linux-amd64.tar.gz</code>.
 </p>
 
 <p>