update document and error message


Chang the spell of armclang

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/include/mbedtls/mbedtls_config.h b/include/mbedtls/mbedtls_config.h
index 293e9cd..3ec19b7 100644
--- a/include/mbedtls/mbedtls_config.h
+++ b/include/mbedtls/mbedtls_config.h
@@ -3217,7 +3217,7 @@
  * for a non-Aarch64 build it will be silently ignored.
  *
  * \note The code uses the SHA-512 Neon intrinsics, so requires GCC >= 8,
- * Clang >= 7 or ArmClang >= 6.10.
+ * Clang >= 7 or armclang >= 6.10.
  *
  * \warning MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT cannot be defined at the
  * same time as MBEDTLS_SHA512_USE_A64_CRYPTO_ONLY.
@@ -3242,7 +3242,7 @@
  * MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT
  *
  * \note The code uses the SHA-512 Neon intrinsics, so requires GCC >= 8,
- * Clang >= 7 or ArmClang >= 6.10.
+ * Clang >= 7 or armclang >= 6.10.
  *
  * \warning MBEDTLS_SHA512_USE_A64_CRYPTO_ONLY cannot be defined at the same
  * time as MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT.