docs: update rendering comparison and license wording

[kiyeonjeon21]

What

This updates a few documentation references after the recent AWS Lambda rendering work:

• Updates the README Remotion comparison row to reflect that HyperFrames now has documented AWS Lambda distributed rendering support.
• Updates the HyperFrames vs Remotion guide so it no longer describes HyperFrames as single-machine-only.
• Keeps the comparison conservative: Remotion Lambda is still described as mature and production-tested, while HyperFrames points readers to the current AWS Lambda docs.
• Corrects the contributing docs license wording from MIT to Apache 2.0, matching the repository LICENSE and README.

Why

Recent releases added the AWS Lambda rendering flow, including lambda deploy, lambda render, lambda render-batch, progress/cost polling, and SDK usage. Some comparison docs still reflected the earlier single-machine-only state, which could confuse adopters evaluating HyperFrames for production rendering.

The contributing docs also had license wording that did not match the repository license.

Notes

Docs-only change. No runtime or API behavior changes.

Validation

• bunx oxfmt --check README.md docs/guides/hyperframes-vs-remotion.mdx docs/contributing.mdx
• git diff --check