Improve description of psa_crypto_input_copy_alloc

Signed-off-by: David Horstmann <david.horstmann@arm.com>
diff --git a/library/psa_crypto_core.h b/library/psa_crypto_core.h
index 3d7198a..87b0035 100644
--- a/library/psa_crypto_core.h
+++ b/library/psa_crypto_core.h
@@ -861,12 +861,12 @@
 
 #define PSA_CRYPTO_LOCAL_INPUT_INIT ((psa_crypto_local_input_t) { NULL, 0 })
 
-/** Allocate a local copy of an input buffer.
+/** Allocate a local copy of an input buffer and copy the contents into it.
  *
  * \param[in] input             Pointer to input buffer.
  * \param[in] input_len         Length of the input buffer.
- * \param[out] local_input      Pointer to a psa_crypto_local_input_t struct to
- *                              populate with the local input copy.
+ * \param[out] local_input      Pointer to a psa_crypto_local_input_t struct
+ *                              containing a local input copy.
  * \return                      #PSA_SUCCESS, if the buffer was successfully
  *                              copied.
  * \return                      #PSA_ERROR_INSUFFICIENT_MEMORY, if a copy of