runbooks/deprecated: add README explaining the deprecation scope ...

Includes the deprecated -> replacement mapping for operators who arrive
  via git log searches or stale internal references.

runbooks: move superseded files to runbooks/deprecated/ ...

These are replaced by v1-do-doc-NN-*.md execution documents (added in
  a prior commit). The 01-destroy-model.md runbook stays in place - it's
  referenced by v1-do-doc-03 as a conditional sub-procedure.

  07-dns-zones.md is deferred to v2 per D-019 with no v1 replacement
  (Designate is no longer in v1 scope).

  History preserved via filesystem rename (git rename detection at
  commit time).