[bug]: docs for peer_pubkey in AddInvoiceRequest need updating

[ZZiigguurraatt]

At

taproot-assets/taprpc/tapchannelrpc/tapchannel.proto

Lines 183 to 188 in e323b9e

	// The node identity public key of the peer to ask for a quote for receiving
	// assets and converting them from satoshis. This must be specified if
	// there are multiple channels with the given asset ID.
	bytes peer_pubkey = 3;

we make no mention of group_key and also is not correct considering the multi-RFQ functionality that is described here.

taproot-assets/taprpc/tapchannelrpc/tapchannel.proto

Lines 36 to 45 in e323b9e

	/* litcli: `ln addinvoice`
	AddInvoice is a wrapper around lnd's lnrpc.AddInvoice method with asset
	specific parameters. It allows RPC users to create invoices that correspond
	to the specified asset amount. If a peer pubkey is specified, then only that
	peer will be used for RFQ negotiations. If none is specified then RFQ quotes
	for all peers with suitable asset channels will be created.
	*/
	rpc AddInvoice (AddInvoiceRequest) returns (AddInvoiceResponse);