ENH: Clarify PATH_SUFFIXES documentation

This clarifies documentation of the find_* commands' PATH_SUFFIXES
option.  The option adds paths with the suffixes but does not remove the
paths without the suffixes.

Source/cmFindBase.cxx

@@ -61,8 +61,10 @@ cmFindBase::cmFindBase()
     "a cmake style list of paths.  For example ENV PATH would be a way "
     "to list the system path variable. The argument "
     "after DOC will be used for the documentation string in "
-    "the cache.  PATH_SUFFIXES can be used to give sub directories "
-    "that will be appended to the search paths.\n"
+    "the cache.  "
+    "PATH_SUFFIXES specifies additional subdirectories to check below "
+    "each search path."
+    "\n"
     "If NO_DEFAULT_PATH is specified, then no additional paths are "
     "added to the search. "
     "If NO_DEFAULT_PATH is not specified, the search process is as follows:\n"