Follow the renames from the review of the view builder

The review of #5620 renamed document_data's tape/tape_size/tape_cap to
nodes/node_count/node_capacity and made the decode arena a
std::vector<char>; adapt the code of this change to it.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

single_include/nlohmann/json_view.hpp

@@ -3225,7 +3225,7 @@ inline void build_object_indexes(document_data& d)
 {
     for (const std::uint32_t i : d.large_objects)
     {
-        build_object_index(d, d.tape + i);
+        build_object_index(d, d.nodes + i);
     }
 }