add space

git-svn-id: https://svn.r-project.org/R/trunk@87438 00db46b3-68df-0310-9c12-caf00c1e9a41

Author: ripley

doc/NEWS.Rd

@@ -294,7 +294,7 @@
       \item \command{R CMD INSTALL} (and hence \command{check}) now by
       default compile C++ code with \code{-DR_NO_REMAP}.  For the time
       being this can be reverted by setting environment
-      variable\env{_R_CXX_USE_NO_REMAP_} to a false value (but that will
+      variable \env{_R_CXX_USE_NO_REMAP_} to a false value (but that will
       be removed in the near future).
 
       `Writing R Extensions' has been revised to describe the remapped