add config.json for samples that need to use S110

I have had a few problems with the sample apps and after much bleating pan (Vincent) came to my rescue, is it worth mentioning the S110 config.json setting, more explicitly so others don't have the same problems. My understanding is that the S110 is for peripheral only so seems the more intuitive soft library for most of the sample apps
off topic ; I really do like the jotta build system and mbed os with C++ wrappers for services etc etc its nicely written