docs(valkey): release notes v2.0.0

[chideat]

What

Wire the v2.0.0 release-notes query templates into the docs build, so the
Jira-published notes for Valkey-v2.0.0 render on the release-notes page the
same way they do for the redis docs.

• doom.config.yml: add releaseNotes.queryTemplates
mw-valkey-v2.0.0-fixed / mw-valkey-v2.0.0-known (ECO project,
  fixVersion-scoped, gated on ReleaseNotesStatus = Publish).
• docs/en/release_notes.mdx: add the ### Fixed Issues / ### Known Issues
  directive sections under 2.0.0, placed before "Before adopting 2.0.0".

No product claims were changed. The compatibility matrix (v2.0.x → Valkey
7.2 / 8.1 / 9.1 → ACP v4.2, v4.3, v4.4) and the lifecycle row already merged in
#15 are the values the release confirmed.

Validation

• yarn lint (doom lint): 0 errors, 0 warnings.
• validate_coupling.py (publish-loop): PASS for v2.0.0 against the ecoscan
  tuple at the tagged tree (3f853d16, server lines 7.2 / 8.1 / 9.1) and the
  operator-confirmed ACP set v4.2,v4.3,v4.4.
• ECO currently has no bug issue on fixVersion = Valkey-v2.0.0, so both
  sections render empty until the first 2.0.x patch publishes notes.
• docs/shared/crds/rds.valkey.buf.red_valkeys.yaml is generated
  (controller-gen) and was flagged, not edited — regenerate from the operator
  source if it drifts.

Opened by publish-loop pub-valkey-200-20260902 (release-loop
rel-valkey-200-20260902, tag v2.0.0 at 3f853d16).

🤖 Generated with Claude Code