[Trivial] Add required missing whitespace to 0.16.0 release notes

Author: harding

_releases/0.16.0.md

@@ -187,6 +187,7 @@ used to create `rpcauth` credentials for a JSON-RPC user.
 ### Validateaddress improvements
 
 The `validateaddress` RPC output has been extended with a few new fields, and support for segwit addresses (both P2SH and Bech32). Specifically:
+
 * A new field `iswitness` is True for P2WPKH and P2WSH addresses ("bc1..." addresses), but not for P2SH-wrapped segwit addresses (see below).
 * The existing field `isscript` will now also report True for P2WSH addresses.
 * A new field `embedded` is present for all script addresses where the script is known and matches something that can be interpreted as a known address. This is particularly true for P2SH-P2WPKH and P2SH-P2WSH addresses. The value for `embedded` includes much of the information `validateaddress` would report if invoked directly on the embedded address.