doc/manual: Render unreleased release notes on master

This renders the rl-next notes when `officialRelease = false`, which
corresponds to the case where we're not on a release branch.

Previously we had disabled this behavior because changelog-d is
somewhat of a heavy dependency, being the only Haskell package.
However, we now have new circumstances that topple the tradeoff.

- We render `master` docs to https://nix.dev/manual/nix/development/release-notes/rl-next.html

- `.#manual` is a separate build now, so `nix build nix/foo` is
  not affected by the increased closure of build input outputs.

Because of these factors, I believe adding this functionality back
is more valuable, as we can use it to

- Previous release notes

- Showcase the upcoming release to the community

packaging/components.nix

@@ -211,6 +211,7 @@ in
 {
   version = baseVersion + versionSuffix;
   inherit versionSuffix;
+  inherit officialRelease;
   inherit maintainers;
 
   inherit filesetToSource;