Clarify go/be --javabase doc to explicitly say a javabase path should be to a directory that contains to a JDK.

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MOS_MIGRATED_REVID=131723746
diff --git a/site/versions/master/docs/bazel-user-manual.html b/site/versions/master/docs/bazel-user-manual.html
index 481a293..baa9800 100644
--- a/site/versions/master/docs/bazel-user-manual.html
+++ b/site/versions/master/docs/bazel-user-manual.html
@@ -1704,10 +1704,11 @@
 
 <h4 id='flag--javabase'><code class='flag'>--javabase (<var>path</var>|<var>label</var>)</code></h4>
 <p>
-  This options set the label or the path of the base Java installation to use
-  for running JavaBuilder, SingleJar, and is also used for bazel run and inside
-  Java binaries built by <code>java_binary</code> rules. The various
-  <a href='be/make-variables.html'>"Make" variables</a> for
+  This option sets the <i>label</i> or the <i>path</i> of the base Java installation to
+  use for running JavaBuilder, SingleJar, for <i>bazel run</i> and <i>bazel
+  test</i>, and for Java binaries built by <code>java_binary</code> and <code>java_test</code>
+  rules. A path must be to a JDK or JRE directory that contains <code>bin/java</code>.
+  The various  <a href='be/make-variables.html'>"Make" variables</a> for
   Java (<code>JAVABASE</code>, <code>JAVA</code>, <code>JAVAC</code> and
   <code>JAR</code>) are derived from this option.
 </p>