Bug 16964: Fix capitalization for "Report Plugins" in reports-home.tt

Bug 16964: Fix capitalization for "Report Plugins" in reports-home.tt

Fix capitalization for "Report Plugins" in reports-home.tt according with
Coding Guidelines <https://wiki.koha-community.org/wiki/Coding_Guidelines#HTML4:_Upper_and_lower_cases_in_strings>

Signed-off-by: Marc <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit 67a65ba16f9c56161fa936a4f80e3f93cfaef167)
Signed-off-by: Frédéric Demians <f.demians@tamil.fr>