Bug 20552: Fix HTML tag for search facets

Bug 20552: Fix HTML tag for search facets

The tags for home library and holding library in the 'refine your
search' list should be h5.

This patch changes the html tag for the availability, holding library and home library
facets.

To test:
- Search for an item in the OPAC where the relevant facet appears
- Use 'Inspect element' to check the tag
- Apply patch
- Confirm the facet now has the h5 tag
- Confirm spacing is improved

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>