Bug 21290: Updating documentation for ModItem

Bug 21290: Updating documentation for ModItem

To test:
Review the patch and check it is now updated correctly

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
(cherry picked from commit 9a5bfee706f85bc5fd53a9c2d0616c2e1186379a)
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
(cherry picked from commit e96eed9b841394353cc5c4484ddc608432e22d29)

Signed-off-by: Jesse Maseto <jesse@bywatersolutions.com>
(cherry picked from commit 3ea009bcc33656e3644ff71cd1fae086bdf3a529)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>