genimage: Fix typo in description

Signed-off-by: Marcus Hoffmann <m.hoffmann@cartelsol.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/genimage/Config.in.host

@@ -5,7 +5,7 @@ config BR2_PACKAGE_HOST_GENIMAGE
 	  images from a given root filesystem tree. genimage is
 	  intended to be run in a fakeroot environment.
 
-	  Configuration is done is a config file parsed by
+	  Configuration is done in a config file parsed by
 	  libconfuse. Options like the path to tools can be given in
 	  environment variables, the config file or commandline
 	  switches.