Bug 32312: Add missing column descriptions to the statistics table

Bug 32312: Add missing column descriptions to the statistics table

This adds missing descriptions to the existing statistics database
columns.

It also improves some existing descriptions.

1. Go to Reports > Guided reports > Create guided report.
2. Choose 'Circulation' for the module to report on and select
   'Next'.
3. Choose 'Tabular' for the type of report and select 'Next'.
4. Scroll down to the statistics table section and note that there
   are no descriptions for:
   - statistics.other
   - statistics.location
   - statistics.ccode
   - statistics.categorycode
5. Note that:
   - the description for statistics.type is 'Type'
   - the description for statistics.itemtype is 'Item type'
6. Apply the patch.
7. Restart all the things (restart_all).
8. Reload the page.
9. Note that:
   . there are now descriptions for the columns in step 4
   . the description for statistics.type is now 'Transaction type'
     (to more clearly indicate what it contains)
   . the description for statistics.itemtype is now 'Koha item type'
     (consistent with other tables where this is used, such as items)
10. Sign off :D

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Andrew Fuerste-Henry <andrewfh@dubcolib.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>