We are slowly dropping support for non-segwit outputs, as proposed in
https://github.com/lightningnetwork/lightning-rfc/pull/894
We can thus safely allow dust limits all the way down to 354 satoshis.
In very rare cases where dust_limit_satoshis is negotiated to a low value,
our peer may generate closing txs that will not correctly relay on the
bitcoin network due to dust relay policies.
When that happens, we detect it and force-close instead of completing the
mutual close flow.
It's useful to have the release notes directly inside the repository
instead of relying on Github: that lets for example users read them offline.
It also lets us fill the release notes every time we add relevant features
on `master` instead of having to do them all at once when we decide to make
a release.