fixup! mention that args can overlap

Author: jonasnick

include/secp256k1_musig.h

@@ -472,7 +472,8 @@ SECP256K1_API int secp256k1_musig_nonce_parity(
  *           invalid (overflowing) values. 1 otherwise (which does NOT mean the
  *           signature or the adaptor are valid!)
  *  Args:         ctx: pointer to a context object
- *  Out:        sig64: 64-byte signature
+ *  Out:        sig64: 64-byte signature. This pointer may point to the same
+ *                     memory area as `pre_sig`.
  *  In:     pre_sig64: 64-byte pre-signature
  *      sec_adaptor32: 32-byte secret adaptor to add to the pre-signature
  *       nonce_parity: the output of `musig_nonce_parity` called with the