Remove outdated note about multiple calls to cipher update for
associated data.

Signed-off-by: Mateusz Starzyk <mateusz.starzyk@mobica.com>
diff --git a/include/mbedtls/cipher.h b/include/mbedtls/cipher.h
index 25e1d8d..4989da7 100644
--- a/include/mbedtls/cipher.h
+++ b/include/mbedtls/cipher.h
@@ -732,8 +732,6 @@
 /**
  * \brief               This function adds additional data for AEAD ciphers.
  *                      Currently supported with GCM and ChaCha20+Poly1305.
- *                      This must be called exactly once, after
- *                      mbedtls_cipher_reset().
  *
  * \param ctx           The generic cipher context. This must be initialized.
  * \param ad            The additional data to use. This must be a readable