sha: fix description for starts functions

Signed-off-by: Valerio Setti <vsetti@baylibre.com>
diff --git a/include/mbedtls/sha512.h b/include/mbedtls/sha512.h
index eb5cef5..2b1fafd 100644
--- a/include/mbedtls/sha512.h
+++ b/include/mbedtls/sha512.h
@@ -99,12 +99,9 @@
  * \param is384    Determines which function to use. This must be
  *                 either \c 0 for SHA-512, or \c 1 for SHA-384.
  *
- * \note           is384 must be defined accordingly with the supported
- *                 symbols in the config file. If:
- *                 - is384 is 0, but \c MBEDTLS_SHA384_C is not defined, or
- *                 - is384 is 1, but \c MBEDTLS_SHA512_C is not defined
- *                 then the function will return
- *                 #MBEDTLS_ERR_SHA512_BAD_INPUT_DATA.
+ * \note           is384 must be defined accordingly to the enabled
+ *                 MBEDTLS_SHA384_C/MBEDTLS_SHA512_C symbols otherwise the
+ *                 function will return #MBEDTLS_ERR_SHA512_BAD_INPUT_DATA.
  *
  * \return         \c 0 on success.
  * \return         A negative error code on failure.