doc: move single change workflow note in contribution guide

The note about the single change workflow is included in the
git-codereview installation instructions, but it has nothing to do with
installing git-codereview. This note is more relevant for when a change
is actually being made.

Change-Id: Iccb90f3b7da87fab863fa4808438cd69a21a2fce
Reviewed-on: https://go-review.googlesource.com/76317Reviewed-by: Steve Francia <spf@golang.org>

doc/contribute.html

@@ -208,12 +208,6 @@ daily work, install the hooks in a new Git checkout by running
 <code>git-codereview</code> <code>hooks</code>.
 </p>
 
-<p>
-The workflow described below assumes a single change per branch.
-It is also possible to prepare a sequence of (usually related) changes in a single branch.
-See the <a href="https://golang.org/x/review/git-codereview">git-codereview documentation</a> for details.
-</p>
-
 <h3 id="git-config">Set up git aliases</h3>
 
 <p>
@@ -429,6 +423,12 @@ In the Go contribution workflow this is done with a <code>git</code>
 directly to that local branch.
 </p>
 
+<p>
+The workflow described here assumes a single change per branch.
+It is also possible to prepare a sequence of (usually related) changes in a single branch.
+See the <a href="https://golang.org/x/review/git-codereview">git-codereview documentation</a> for details.
+</p>
+
 <pre>
 $ git change <i>&lt;branch&gt;</i>
 </pre>