org-manual: Fix `org-latex-subtitle-format' documentation

* doc/org-manual.org (LaTeX specific export settings): Fix
`org-latex-subtitle-format' documentation.

doc/org-manual.org

@@ -13166,7 +13166,7 @@ general options (see [[*Export Settings]]).
   #+vindex: org-latex-subtitle-format
   The document's subtitle.  It is typeset as per
   ~org-latex-subtitle-format~.  If ~org-latex-subtitle-separate~ is
-  non-~nil~, it is typed as part of the ~\title~ macro.  See
+  non-~nil~, it is typed outside of the ~\title~ macro.  See
   ~org-latex-hyperref-template~ for customizing metadata items.  See
   ~org-latex-title-command~ for typesetting description into the
   document's front matter.