bonnie: Expand description in config help text.

The description "Filesystem tester" is rather unhelpful. Take the
description from the referenced web site to make it a bit clearer what
bonnie++ actually is.

[Thomas: rewrap Config.in help text.]

Signed-off-by: Cam Hutchison <camh@xdna.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/bonnie/Config.in

@@ -3,7 +3,8 @@ config BR2_PACKAGE_BONNIE
 	depends on BR2_INSTALL_LIBSTDCPP
 	depends on BR2_USE_MMU # fork()
 	help
-	  Filesystem tester
+	  A benchmark suite that is aimed at performing a number of
+	  simple tests of hard drive and file system performance.
 
 	  http://www.coker.com.au/bonnie++/