doc/install.html: fix a tag.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/30900044

doc/install.html

@@ -98,12 +98,12 @@ variable. You can do this by adding this line to your <code>/etc/profile</code>
 export PATH=$PATH:/usr/local/go/bin
 </pre>
 
-<h4 id="tarball_non_standard">Installing to a custom location</h3>
+<h4 id="tarball_non_standard">Installing to a custom location</h4>
 
 <p>
 The Go binary distributions assume they will be installed in
 <code>/usr/local/go</code> (or <code>c:\Go</code> under Windows),
-but it is possible to install the Go tools to a different location. 
+but it is possible to install the Go tools to a different location.
 In this case you must set the <code>GOROOT</code> environment variable
 to point to the directory in which it was installed.
 </p>
@@ -234,7 +234,7 @@ You just need to do a little more setup.
 </p>
 
 <p>
-The <a href="/doc/code.html">How to Write Go Code</a> document 
+The <a href="/doc/code.html">How to Write Go Code</a> document
 provides <b>essential setup instructions</b> for using the Go tools.
 </p>