Document that --build_tag_filters does not affect test targets when running `blaze test`.

#8439

PiperOrigin-RevId: 325117049

site/docs/user-manual.html

diff --git a/site/docs/user-manual.html b/site/docs/user-manual.html
index ed2c99c6..fb5f9ad 100644
--- a/site/docs/user-manual.html
+++ b/site/docs/user-manual.html
@@ -1127,6 +1127,11 @@
   preceded with '-' sign used to denote excluded tags. Required tags may also
   have a preceding '+' sign.
 </p>
+<p>
+  When running tests, Bazel ignores <code class='flag'>--build_tag_filters</code> for test targets,
+  which are built and run even if they do not match this filter. To avoid building them, filter
+  test targets using <code class='flag'>--test_tag_filters</code> or by explicitly excluding them.
+</p>
 
 <h4 id='flag--test_size_filters'><code class='flag'>--test_size_filters <var>size[,size]*</var></code></h4>
 <p>