docs(lambda): drop plan-doc reference from migration checklist

PR review feedback: source/docs should not mention the
distributed-rendering planning doc. Tighten the migration checklist
sentence to describe the webm path directly rather than referencing
the doc's version label.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: jrusso1020

docs/deploy/migrating-to-hyperframes-lambda.mdx

@@ -80,7 +80,7 @@ The default policy doc emitted by `hyperframes lambda policies user/role` uses `
 
 ## Migration checklist
 
-1. **Inventory** the compositions you want to migrate. Filter out anything that needs HDR — that stays on your current framework for now. webm renders distributed-mode under v1.5 via closed-GOP VP9.
+1. **Inventory** the compositions you want to migrate. Filter out anything that needs HDR — that stays on your current framework for now. webm renders distributed via closed-GOP VP9 + concat-copy (see the webm section above).
 2. **Translate** each composition to plain HTML. The `[Concepts](/concepts)` page covers the data-attribute conventions; the `/hyperframes` skill (`npx skills add heygen-com/hyperframes`) makes Claude / Cursor / Codex aware of them too.
 3. **Wire** the new composition into your build pipeline alongside the old one. HyperFrames doesn't need an external bundler — you can `npx hyperframes preview` against the HTML directly.
 4. **Deploy** in a separate AWS account or with a `--stack-name=hyperframes-staging` first. Run a real render with `--wait`; verify the output bytes.