Bug 27740: (QA follow-up) Fix 'Payment method'

Bug 27740: (QA follow-up) Fix 'Payment method'

The 'Payment method' heading now needs to be moved to the second level
to ensure consistent header heirarchy.

Test plan
1/ Add some debts to a patrons account
2/ Enable online payments (Paypal is a good example)
3/ Login to the OPAC and navigate to the 'Charges' page
4/ Note the header hierarchy has no gaps... (h1 -> h2, not h1 -> h3)

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Wainui Witika-Park <wainuiwitikapark@catalyst.net.nz>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>