Update include/picotls.h

Co-authored-by: Kazuho Oku <kazuhooku@gmail.com>
diff --git a/include/picotls.h b/include/picotls.h
index ca25ef3..90a3e53 100644
--- a/include/picotls.h
+++ b/include/picotls.h
@@ -1230,7 +1230,7 @@
  */
 void ptls_aead_free(ptls_aead_context_t *ctx);
 /**
- * Permutates the static IV by applying given bytes using bit-wise XOR. This API can be used for supplying nonces longer than 64-
+ * Permutes the static IV by applying given bytes using bit-wise XOR. This API can be used for supplying nonces longer than 64-
  * bits.
  */
 static void ptls_aead_xor_iv(ptls_aead_context_t *ctx, const void *bytes, size_t len);