[Native SSO] Typo in the OP native_sso_supported metadata parameter

[Vladimir Dzhuvinov]

The OP metadata parameter to indicate native SSO support is declared as native_sso_supported:

https://openid.net/specs/openid-connect-native-sso-1_0.html#section-7.2.1

In section 5 the parameter is given as native_sso_support, should be `native_sso_supported`:

https://openid.net/specs/openid-connect-native-sso-1_0.html#name-discovery-metadata

( `*_supported` is the established OP metadata naming pattern)