Add trusted gem publishing

README.md

@@ -33,6 +33,10 @@ During the alpha series both gems are pinned in lockstep. Version 0.0.1.alpha6
 uses a subscribe-ready-before-prompt transport contract and reconnects an
 accepted turn without posting its prompt again.
 
+Releases use RubyGems trusted publishing. Register `release.yml` as the gem's
+trusted publisher (using the `release` environment); after that, a `v*` tag
+publishes without a long-lived RubyGems API key.
+
 ## Quickstart
 
 ```ruby