message: Mention removal of libp2p support in changelog
diff: @@ -31,6 +31,7 @@ All notable changes to this project will be documented in this file. The format
  ### Removed
  * The unofficial support for nix-related derivations and support tooling has been removed.
  * Experimental, nix-based kubernetes testing support has been removed.
  +* Experimental support for libp2p has been removed.
  