orgguide.texi: Fix typo

* doc/orgguide.texi (TODO Items): Fix typo.

Reported-by: siraben@disroot.org
<http://lists.gnu.org/r/emacs-orgmode/2018-03/msg00036.html>

doc/orgguide.texi

@@ -846,7 +846,7 @@ come up while taking notes!  With Org mode, simply mark any entry in a tree
 as being a TODO item.  In this way, information is not duplicated, and TODO
 items remain in the context from which they emerged.
 
-Org mode providing methods to give you an overview of all the things that you
+Org mode provides methods to give you an overview of all the things that you
 have to do, collected from many files.
 
 @menu