schema parsers CHANGE improve error message text

clarify that the error is connected with leafref type
diff --git a/src/tree_schema.c b/src/tree_schema.c
index 8c97e18..06bcf69 100644
--- a/src/tree_schema.c
+++ b/src/tree_schema.c
@@ -3716,7 +3716,7 @@
     /* check for config flag */
     if ((leafref->flags & LYS_CONFIG_W) && (leafref_target->flags & LYS_CONFIG_R)) {
         LOGVAL(LYE_SPEC, LY_VLOG_LYS, leafref,
-               "The %s is config but refers to a non-config %s.",
+               "The leafref %s is config but refers to a non-config %s.",
                strnodetype(leafref->nodetype), strnodetype(leafref_target->nodetype));
         return -1;
     }