Fix doc reference to EVP_AEAD_max_overhead

The documentation referred to the old name of EVP_AEAD_overhead.

Change-Id: Ifaaf1a703686935bba561a70ecace76f0dd0c290
diff --git a/src/include/openssl/aead.h b/src/include/openssl/aead.h
index 6fd8116..61cf3cd 100644
--- a/src/include/openssl/aead.h
+++ b/src/include/openssl/aead.h
@@ -227,8 +227,8 @@
  *
  * At most |max_out_len| bytes are written to |out| and, in order to ensure
  * success, |max_out_len| should be |in_len| plus the result of
- * |EVP_AEAD_overhead|. On successful return, |*out_len| is set to the actual
- * number of bytes written.
+ * |EVP_AEAD_max_overhead|. On successful return, |*out_len| is set to the
+ * actual number of bytes written.
  *
  * The length of |nonce|, |nonce_len|, must be equal to the result of
  * |EVP_AEAD_nonce_length| for this AEAD.