Update release notes.

Author: ioquatix

releases.md

@@ -1,5 +1,11 @@
 # Releases
 
+## Unreleased
+
+  - 100% test and documentation coverage.
+  - {Protocol::Rack::Input#rewind} now works when the entire input is already read.
+  - {Protocol::Rack::Adapter::Rack2} has stricter validation of the application response.
+  
 ## v0.12.0
 
   - Ignore (and close) response bodies for status codes that don't allow them.