The parameter CustomerIDRaw is not documented in Kernel::System::CustomerUser::CustomerSearch()

[bschmalhofer]

In OTOBO core there are two data backends for Kernel::System::CustomerUser. These are LDAP and the DB backend. Both support the parameter CustomerIDRaw. But the parameter is not documented in Kernel/System/CustomerUser.pm.

While at it, document the diverging behavior of the CustomerID parameter.