Add note that uECC_VLI_NATIVE_LITTLE_ENDIAN affects key compatiblity
diff --git a/uECC.h b/uECC.h
index 9911763..43a19d6 100644
--- a/uECC.h
+++ b/uECC.h
@@ -44,7 +44,10 @@
translations are required.
Note that this will *only* work on native little-endian processors and it will treat the uint8_t
arrays passed into the public API as word arrays, therefore requiring the provided byte arrays
-to be word aligned on architectures that do not support unaligned accesses. */
+to be word aligned on architectures that do not support unaligned accesses.
+IMPORTANT: Keys and signatures generated with uECC_VLI_NATIVE_LITTLE_ENDIAN=1 are incompatible
+with keys and signatures generated with uECC_VLI_NATIVE_LITTLE_ENDIAN=0; all parties must use
+the same endianness. */
#ifndef uECC_VLI_NATIVE_LITTLE_ENDIAN
#define uECC_VLI_NATIVE_LITTLE_ENDIAN 0
#endif
