Help: Update GoogleTest XML_OUTPUT_DIR release note markup

Help/release/dev/GoogleTest-XML_OUTPUT_DIR.rst

@@ -1,6 +1,6 @@
 GoogleTest-XML_OUTPUT_DIR
 -------------------------
 
-* The :module:`GoogleTest` module ``gtest_discover_test`` command
+* The :module:`GoogleTest` module :command:`gtest_discover_tests` command
   gained a new optional parameter ``XML_OUTPUT_DIR``. When set the JUnit XML
   test results are stored in that directory.