discv5_updateNodeInfo endpoint: socker parameter format

[meldsun0]

When implementing discv5_updateNodeInfo I noticed that the format suggested, is for ip4. Is this correct or the socket parameter should be a multiaddress ? If that is the case the attribute isTcp may not be necessary.

[kdeme]

This PR is related (but a bit more broad) to this issue: #207

Not much priority on this however as the method is nowhere used (so we could also just remove it).