doc/go1.5.html: update references to runtime/trace package

Tracing functionality was moved from runtime/pprof to runtime/trace.

Change-Id: I694e0f209d043c7ffecb113f1825175bf963dde3
Reviewed-on: https://go-review.googlesource.com/13074Reviewed-by: Rob Pike <r@golang.org>

doc/go1.5.html

@@ -1222,14 +1222,14 @@ adds new <a href="/pkg/os/signal/#Ignore"><code>Ignore</code></a> and
 
 <li>
 The <a href="/pkg/runtime/"><code>runtime</code></a>,
-<a href="/pkg/runtime/pprof/"><code>runtime/pprof</code></a>,
+<a href="/pkg/runtime/pprof/"><code>runtime/trace</code></a>,
 and <a href="/pkg/net/http/pprof/"><code>net/http/pprof</code></a> packages
 each have new functions to support the tracing facilities described above:
 <a href="/pkg/runtime/#ReadTrace"><code>ReadTrace</code></a>,
 <a href="/pkg/runtime/#StartTrace"><code>StartTrace</code></a>,
 <a href="/pkg/runtime/#StopTrace"><code>StopTrace</code></a>,
-<a href="/pkg/runtime/pprof/#StartTrace"><code>StartTrace</code></a>,
-<a href="/pkg/runtime/pprof/#StopTrace"><code>StopTrace</code></a>, and
+<a href="/pkg/runtime/trace/#Start"><code>Start</code></a>,
+<a href="/pkg/runtime/trace/#Stop"><code>Stop</code></a>, and
 <a href="/pkg/net/http/pprof/#Trace"><code>Trace</code></a>.
 See the respective documentation for details.
 </li>