Add note that uECC_VLI_NATIVE_LITTLE_ENDIAN affects key compatiblity
Add note that uECC_VLI_NATIVE_LITTLE_ENDIAN affects key compatiblity

kmackay/micro-ecc,adfernandes/micro-ecc,kmackay/micro-ecc,adfernandes/micro-ecc,adfernandes/micro-ecc,adfernandes/micro-ecc,kmackay/micro-ecc,kmackay/micro-ecc