Fix incorrect anchor tag in Bazel user guide
Fixes
RELNOTES: None.
@@ -103,7 +103,7 @@ title: User's Guide
prints which targets were requested, whether or not they were
successfully built, and if so, where the output files can be found.
Scripts that run builds can reliably parse this output; see <a
- href='#flag--show_result'><code class='flag'>--show_result</code></a> for more
+ href='user-manual.html#flag--show_result'><code class='flag'>--show_result</code></a> for more
details.
</p>
<p>
