fixup! Address jesseposner's comments

include/secp256k1_schnorrsig.h

@@ -23,16 +23,16 @@ extern "C" {
  *
  *  Returns: 1 if a nonce was successfully generated. 0 will cause signing to
  *           return an error.
- *  Out:  nonce32: pointer to a 32-byte array to be filled by the function.
+ *  Out:  nonce32: pointer to a 32-byte array to be filled by the function
  *  In:       msg: the message being verified (will not be NULL)
  *         msglen: the length of the message (will not be NULL)
  *          key32: pointer to a 32-byte secret key (will not be NULL)
  *     xonly_pk32: the 32-byte serialized xonly pubkey corresponding to key32
  *                 (will not be NULL)
  *           algo: pointer to an array describing the signature
- *                 algorithm (will not be NULL).
+ *                 algorithm (will not be NULL)
  *        algolen: the length of the algo array
- *           data: Arbitrary data pointer that is passed through.
+ *           data: arbitrary data pointer that is passed through
  *
  *  Except for test cases, this function should compute some cryptographic hash of
  *  the message, the key, the pubkey, the algorithm description, and data.
@@ -98,15 +98,16 @@ typedef struct {
  *  abort if it fails.
  *
  *  This function only signs 32-byte messages. If you have messages of a
- *  different size, it is recommended to create a 32-byte message hash with
+ *  different size (or the same size but without an application-specific tag
+ *  prefix), it is recommended to create a 32-byte message hash with
  *  secp256k1_tagged_sha256 and then sign the hash. Tagged hashing allows
  *  providing an application-specific tag for domain separation. This prevents
  *  signatures from being valid in multiple applications by accident.
  *
  *  Returns 1 on success, 0 on failure.
  *  Args:    ctx: pointer to a context object, initialized for signing (cannot be NULL)
  *  Out:   sig64: pointer to a 64-byte array to store the serialized signature (cannot be NULL)
- *  In:    msg32: the 32-byte message hash being signed (cannot be NULL)
+ *  In:    msg32: the 32-byte message being signed (cannot be NULL)
  *       keypair: pointer to an initialized keypair (cannot be NULL)
  *    aux_rand32: 32 bytes of fresh randomness. While recommended to provide
  *                this, it is only supplemental to security and can be NULL. See