Merge bitcoin-core#631: typo in comment for secp256k1_ec_pubkey_tweak_mul ()

6914c25 typo in comment for secp256k1_ec_pubkey_tweak_mul () (philsmd)

Pull request description:

  Fixes a typo in secp256k1.h documentation

ACKs for commit 6914c2:

Tree-SHA512: 9b95209b7decab4624054b5e3476e99468f84f84eb270bba997abf73a78acbbf2eaa094dfa367ebfe0b1e553329071e9a0ca8a1e2b31ea7fbc4aad3fb0665e88

Author: gmaxwell

include/secp256k1.h

@@ -646,7 +646,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_mul(
  *          uniformly random 32-byte arrays, or equal to zero. 1 otherwise.
  * Args:    ctx:    pointer to a context object initialized for validation
  *                 (cannot be NULL).
- * In/Out:  pubkey: pointer to a public key obkect.
+ * In/Out:  pubkey: pointer to a public key object.
  * In:      tweak:  pointer to a 32-byte tweak.
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_mul(