Bug 15552: Better wording of intranetreadinghistory

Bug 15552: Better wording of intranetreadinghistory

To test:

1) Find intranetreadinghistory system preference in Administration
2) Confirm new description gives more information and makes sense

Signed-off-by: Hector Castro <hector.hecaxmmx@gmail.com>
Better wording and much better for translatability purposes

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Brendan A Gallagher <brendan@bywatersolutions.com>
(cherry picked from commit c827160122525c45000a4208215ee3fd83aa92b0)
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>