Link PSA_KEY_TYPE_PASSWORD in the documentation

Signed-off-by: Janos Follath <janos.follath@arm.com>
diff --git a/include/psa/crypto.h b/include/psa/crypto.h
index e94a957..8759d69 100644
--- a/include/psa/crypto.h
+++ b/include/psa/crypto.h
@@ -4328,7 +4328,7 @@
  *                              value derived from the password (eg. by a
  *                              memory-hard function).  It must remain valid
  *                              until the operation terminates. It must be of
- *                              type PSA_KEY_TYPE_PASSWORD or
+ *                              type #PSA_KEY_TYPE_PASSWORD or
  *                              #PSA_KEY_TYPE_DERIVE. It has to allow the usage
  *                              #PSA_KEY_USAGE_DERIVE.
  *