scripts/spdxcheck: Exclude top-level README

Nothing copyrightable to see here.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

scripts/spdxexclude

@@ -15,3 +15,4 @@ arch/*/configs/
 # Other files without copyrightable content
 /CREDITS
 /MAINTAINERS
+/README