doc: Correct sentence in README

Usage of 'save for/safe for' here could be confusing for non-native
English speakers. Rather than fix the typo, let's use the more commonly
understand 'except'.

Signed-off-by: Rhys Kidd <rhyskidd@gmail.com>
Reviewed-by: Petri Latvala <petri.latvala@intel.com>
1 file changed