[Rd] trivial typo in NEWS file

[Ben Bolker]

   Index: doc/NEWS.Rd
===================================================================
--- doc/NEWS.Rd	(revision 81435)
+++ doc/NEWS.Rd	(working copy)
@@ -425,7 +425,7 @@
        data frames with default row names (Thanks to Charlie Gao's
        \PR{18179}).

-      \item \code{txtProgresBar()} now enforces a non-zero width for
+      \item \code{txtProgressBar()} now enforces a non-zero width for
        \code{char}, without which no progress can be visible.

        \item \code{dimnames(table(d))} is more consistent in the case where