Bug 12026: [QA Follow-up] POD typo and tiny change in AddMember_Opac

Bug 12026: [QA Follow-up] POD typo and tiny change in AddMember_Opac

[1] Correct xml error in POD
Copy-pasting this example from Auth_with_shibboleth.pm into koha-conf.xml
did not work. We need a closing tag ;)
[2] If AddMember_Opac calls AddMember_Auto, there is no need to call
fixup_cardnumber. Adding trivial test for AddMember_Auto in Members.t.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Olli-Antti Kivilahti <olli-antti.kivilahti@jns.fi>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>