export.yml comment refers to invalid "list of statistics" URL

Both `export.yml` & `export.yml.j2` both have a comment:

`For more info refer to: https://docs.weka.io/usage/statistics/list-of-statistics`

That URL is a 404.

I think it needs to be updated to `https://docs.weka.io/operation-guide/statistics/statistics-list` instead ?