update usage description for c81793 and c85665

git-svn-id: https://svn.r-project.org/R/trunk@87608 00db46b3-68df-0310-9c12-caf00c1e9a41

Author: smeyer

src/library/tools/R/check.R

@@ -6891,10 +6891,9 @@ add_dummies <- function(dir, Log)
             "",
             "A variety of diagnostic checks on directory structure, index and",
             "control files are performed.  The package is installed into the log",
-            "directory and production of the package PDF manual is tested.",
+            "directory and production of the package manual is tested.",
             "All examples and tests provided by the package are tested to see if",
-            "they run successfully.  By default code in the vignettes is tested,",
-            "as is re-building the vignette PDFs.",
+            "they run successfully. Vignettes are re-made from their sources.",
             "",
             "Options:",
             "  -h, --help            print short help message and exit",