typo in grid vignette (thanks to Michael Chirico)

git-svn-id: https://svn.r-project.org/R/trunk@87800 00db46b3-68df-0310-9c12-caf00c1e9a41

Author: murrell

src/library/grid/vignettes/grid.Rnw

@@ -93,7 +93,7 @@ grid.show.viewport(viewport(x = 0.5, y = 0.5, width = 0.5, height = 0.25,
 \caption{
   \label{figure:viewport}
   A diagram of a simple \grid{} viewport (produced using the
-  \code{grid.show.viewport()} function.}
+  \code{grid.show.viewport()} function).}
 \end{figure}
 
 The object returned by the \code{viewport()} function is only a