Doc: clarify the preconditions for psa_cipher_update
diff --git a/include/psa/crypto.h b/include/psa/crypto.h
index 4b2e9a0..8a80620 100644
--- a/include/psa/crypto.h
+++ b/include/psa/crypto.h
@@ -1963,12 +1963,12 @@
/** Encrypt or decrypt a message fragment in an active cipher operation.
*
- * The application must call psa_cipher_encrypt_setup() or
- * psa_cipher_decrypt_setup() before calling this function. The choice
- * of setup function determines whether this function encrypts or
- * decrypts its input. After calling a setup function, if the chosen
- * algorithm requires an IV, the application must call
- * psa_cipher_generate_iv() or psa_cipher_set_iv().
+ * Before calling this function, you must:
+ * 1. Call either psa_cipher_encrypt_setup() or psa_cipher_decrypt_setup().
+ * The choice of setup function determines whether this function
+ * encrypts or decrypts its input.
+ * 2. If the algorithm requires an IV, call psa_cipher_generate_iv()
+ * (recommended when encrypting) or psa_cipher_set_iv().
*
* If this function returns an error status, the operation becomes inactive.
*