docs(release): point distribution status at Maven Central + javadoc.io (H3) (#99)

Wires up Track H3 — hosted Javadocs. javadoc.io auto-mirrors any artefact published to Maven Central within minutes, so no separate hosting infrastructure is required; this PR just updates the README distribution status note to point callers at the URL.

README distribution note revision:

  Was: 'currently JitPack. Maven Central is planned for v1.7'

  Now: 'currently JitPack. Maven Central ships from v1.6.6 under coordinates io.github.demchaav:graphcompose. Hosted Javadocs auto-publish to javadoc.io. JitPack stays available alongside.'

The full Central install snippet ('Central as primary, JitPack as fallback') lands in the v1.6.6 release-prep PR after the first Central publish proves the pipeline end-to-end. This PR is the lightweight documentation step that's safe to ship now without waiting on the actual publish event.

Verification: ./mvnw test -pl . -Dtest='CanonicalSurfaceGuardTest,DocumentationCoverageTest,VersionConsistencyGuardTest' -> 13 tests, 0 failures (~18s).

Author: DemchaAV

CHANGELOG.md

@@ -46,6 +46,16 @@ JitPack continue to resolve through the existing coordinates.
   secrets, and the release-candidate dry-run strategy. § 2.B
   post-release checklist gains a new step 9 for the Central publish
   alongside the existing JitPack step.
+- **Hosted Javadocs via `javadoc.io`** (Track H3). README's
+  distribution-status note now points callers at
+  [javadoc.io/doc/io.github.demchaav/graphcompose](https://javadoc.io/doc/io.github.demchaav/graphcompose),
+  which auto-mirrors any artefact published to Maven Central within
+  minutes — no separate hosting infrastructure required. The note
+  also pins Maven Central as the going-forward primary distribution
+  starting v1.6.6 (JitPack stays available alongside for existing
+  callers). The full Central install snippet ("Central as primary,
+  JitPack as fallback") lands in the v1.6.6 release-prep PR after the
+  first Central publish proves the pipeline end-to-end.
 - **`central-publishing-maven-plugin` in the `release` profile**
   (Track D3). Adds Sonatype's `central-publishing-maven-plugin` 0.7.0
   to the existing `release` profile as a packaging extension. Replaces

README.md

@@ -104,7 +104,10 @@ repositories { maven("https://jitpack.io") }
 dependencies { implementation("com.github.demchaav:GraphCompose:v1.6.5") }
 ```
 
-> **Distribution status** — currently **JitPack**. Maven Central is planned for v1.7 ([tracking issue](https://github.com/DemchaAV/GraphCompose/issues/7)).
+> **Distribution status** — currently **JitPack**. **Maven Central**
+> ships from **v1.6.6** under coordinates `io.github.demchaav:graphcompose:<version>`;
+> hosted Javadocs auto-publish to [javadoc.io/doc/io.github.demchaav/graphcompose](https://javadoc.io/doc/io.github.demchaav/graphcompose) shortly after each Central release.
+> JitPack stays available alongside Central for existing callers.
 
 > **Upgrading from v1.5?** Core document authoring stays source-compatible &mdash; engine, DSL, themes, and backend-neutral records carry v1.5 callers unchanged. **Templates v2** replaces the legacy CV / cover-letter template classes; legacy classes were **deleted**, not deprecated. Read the [migration guide](./docs/roadmaps/migration-v1-5-to-v1-6.md) before upgrading template-heavy code.