It certainly changes. Actually we have automatic regeneration which stores pages on GitHub, you may see it [here](http://pointcloudlibrary.github.io/documentation/index.html).
And the page with index `a01791` is currently ['random.hpp'](http://pointcloudlibrary.github.io/documentation/a01791_source.html), not 'point_types.hpp'.

The GitHub address would be: https://github.com/PointCloudLibrary/pcl/blob/master/common/include/pcl/impl/point_types.hpp