x-fapi-customer-ip-address should probably have an example for ipv6

[Joseph Heenan]

Some UK banks apparently reject requests where x-fapi-customer-ip-address contains an IPv6 address. Just for clarity, we should add an IPv6 example in the spec.

( https://gitlab.com/openid/conformance-suite/-/issues/761 has been opened to consider adding checks for this in the conformance suite.)

[Daniel Fett]

With IPv4 being deprecated, the IPv6 example should probably come before the IPv4 example.

[Daniel Fett]

I added an example in FAPI 2 Baseline in this branch: https://bitbucket.org/openid/fapi/branch/danielfett/fapi2/advanced

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[Dave Tonge]

https://bitbucket.org/openid/fapi/pull-requests/169/add-ipv6-example