Specify the differences in searching leases from DHCPv4 and v6

The issue was reported on our mailing list.

The IPv4 leases can be searched by:

IP address
MAC address
Client ID
hostname

and IPv6 leases can be searched by:

IP address
DUID
hostname

but the help tip mixes all these possibilities together which is confusing for users. We should clearly specify that the IPv6 leases can't be filtered by MAC address or Client ID.

Use the input box to specify a searched lease. You can search the lease by one of the following lease properties:

IP address

delegated prefix (excluding prefix length)

MAC address

DHCPv4 client identifier

DHCPv6 DUID

hostname

MAC address, client identifier and DUID can be specified in the following formats:

01:02:03:04:05

01 02 03 04 05

0102030405