doc: restore race detector manual
This got deleted mistakenly during the content re-org.
Fixes #7275.
LGTM=dvyukov
R=golang-codereviews, minux.ma, dvyukov
CC=golang-codereviews
https://golang.org/cl/60850043
diff --git a/doc/docs.html b/doc/docs.html
index 7aad8da..212f345 100644
--- a/doc/docs.html
+++ b/doc/docs.html
@@ -143,7 +143,8 @@
<li><a href="/doc/gdb">Debugging Go Code with GDB</a></li>
<li><a href="/blog/godoc-documenting-go-code">Godoc: documenting Go code</a> - writing good documentation for <a href="/cmd/godoc/">godoc</a>.</li>
<li><a href="/blog/profiling-go-programs">Profiling Go Programs</a></li>
-<li><a href="/blog/race-detector">Data Race Detector</a> - testing Go programs for race conditions.</li>
+<li><a href="/doc/articles/race_detector.html">Data Race Detector</a> - a manual for the data race detector.</li>
+<li><a href="/blog/race-detector">Introducing the Go Race Detector</a> - an introduction to the race detector.
</ul>
<h4 id="articles_more">More</h4>
