hash_clone: Fix copypasta and add a functional description
diff --git a/include/psa/crypto.h b/include/psa/crypto.h
index e639906..373c123 100644
--- a/include/psa/crypto.h
+++ b/include/psa/crypto.h
@@ -923,6 +923,15 @@
 
 /** Clone a hash operation.
  *
+ * This function copies the state of an ongoing hash operation to
+ * a new operation object. In other words, this function is equivalent
+ * to calling psa_hash_setup() on \p target_operation with the same
+ * algorithm that \p source_operation was set up for, then
+ * psa_hash_update() on \p target_operation with the same input that
+ * that was passed to \p source_operation. After this function returns, the
+ * two objects are independent, i.e. subsequent calls involving one of
+ * the objects do not affect the other object.
+ *
  * \param[in] source_operation      The active hash operation to clone.
  * \param[in,out] target_operation  The operation object to set up.
  *                                  It must be initialized but not active.
@@ -931,7 +940,7 @@
  * \retval #PSA_ERROR_BAD_STATE
  *         \p source_operation is not an active hash operation.
  * \retval #PSA_ERROR_BAD_STATE
- *         \p source_operation is active.
+ *         \p target_operation is active.
  * \retval #PSA_ERROR_COMMUNICATION_FAILURE
  * \retval #PSA_ERROR_HARDWARE_FAILURE
  * \retval #PSA_ERROR_TAMPERING_DETECTED