We don't support it (yet), but update the spec to include it.
We include the previous field (recurrence_signature) as a shim for the
moment, for compat with existing nodes. It's ugly, but next release
we'll stop *sending* it, then finally we'll stop accepting it!
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
For some reason, an old version was checked in. We don't currently
use it (since bolt12 support depends on EXPERIMENTAL_FEATURES, which
uses bolt12_exp_wire.csv, which is generated and not checked in).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
