Fix command line syntax of `org-batch-store-agenda-view'

* org.texi (Exporting Agenda Views): Fix command line syntax.

You cannot use 'emacs -f org-batch-store-agenda-view' because it is
implemented as macro, not function.

doc/org.texi

@@ -8587,7 +8587,7 @@ in @code{org-agenda-custom-commands} take precedence.
 @noindent
 From the command line you may also use
 @example
-emacs -f org-batch-store-agenda-views -kill
+emacs -eval (org-batch-store-agenda-views) -kill
 @end example
 @noindent
 or, if you need to modify some parameters@footnote{Quoting depends on the