doc-schema: make address field in getinfo response required

[RCasatta]

Since it is always returned even if empty this was false, see #5904 (comment) , there are cases where address field is not returned, but since there are also cases where is returned empty the issue remains.

alternative to #5902
Closes #5902
Changelog-None

[cdecker]

Following the discussion on #5902 it feels like this breaks fewer things. Apologies for suggesting #5902 first :-)

[cdecker]

To spell out the various combinations:

• New client, new node: business as usual
• Old client, old node: business as usual
• New client, old node: node (cln-grpc with old proto) may skip serializing the empty array, client sees it missing, and initializes it with the default.
• Old client, new node: node serializes empty array, which would have been omitted before, client deserializes empty array.

The only downside I can see with this is the couple of extra bytes for serializing the empty array, whereas the old code would just omit it. No big deal.

[vincenzopalazzo]

ACK 8da5c7f

I preferer this, but I do not have the big picture of the problem

[rustyrussell]

But the code shows this is trivially untrue?

	/* Add network info */
	if (cmd->ld->listen) {
		/* These are the addresses we're announcing */
		count_announceable = tal_count(cmd->ld->announceable);
		json_array_start(response, "address");

So, run with --offline, and you'll see no address.

[RCasatta]

But the code shows this is trivially untrue?

Right, so I updated this to add an empty address array even if --offline is set
and I also updated this MR description

[RCasatta]

but I do not have the big picture of the problem

The reason I am doing this is that If the field is optional and I have a getinfo json A with the address field empty,
if I do json A -> grpc -> json B the B json will not match A because it will skip serializing an empty optional field.

[vincenzopalazzo]

ACK 2dc70b5

[rustyrussell]

Trivial rebase for conflict.

Ack 297b5e4

[rustyrussell]

Trivial rebase for man page checksum conflict

Ack 58566cb