Write missing bit of the documentation of psa_key_derivation
@@ -3040,7 +3040,10 @@ psa_status_t psa_generator_abort(psa_crypto_generator_t *generator);
* and \p label is the info string used in the "expand" step.
*
* \param[in,out] generator The generator object to set up. It must
- * have been initialized to .
+ * have been initialized to all-bits-zero,
+ * a logical zero (`{0}`),
+ * \c PSA_CRYPTO_GENERATOR_INIT or
+ * psa_crypto_generator_init().
* \param key Slot containing the secret key to use.
* \param alg The key derivation algorithm to compute
* (\c PSA_ALG_XXX value such that
