docs: refresh contributing & building guides, surface CLA signing flow (#15503)

README.md

@@ -97,7 +97,7 @@ Thanks for checking us out, we appreciate your interest and sincerely hope that
 
 Calling all developers, testers, tech writers and more! Contributions of all types are more than welcome, you can read more in [docs/types-of-contributions.md](docs/types-of-contributions.md). If you are interested in contributing code, read our [docs/CONTRIBUTING.md](docs/CONTRIBUTING.md) and feel free to check out our GitHub issues to get stuck in to show us what you’re made of.
 
-**Before you start contributing, please make sure you have read and accepted our [Contributor License Agreement]. To indicate your agreement, simply edit this file and submit a pull request.**
+**Before you start contributing, please sign our [Contributor License Agreement] — it takes less than a minute with your GitHub account. Pull requests cannot be merged until every committer has signed (the `license/cla` check on your PR). Full text: [CLA.md](.github/CLA.md).**
 
 For **bug reports**, **feature requests** and other **suggestions** you can also [create a new issue](https://github.com/toeverything/AFFiNE/issues/new/choose) and choose the most appropriate template for your feedback.
 
@@ -216,10 +216,9 @@ See [LICENSE] for details.
 [update page]: https://affine.pro/blog?tag=Release%20Note
 [jobs available]: ./docs/jobs.md
 [latest packages]: https://github.com/toeverything/AFFiNE/pkgs/container/affine-self-hosted
-[contributor license agreement]: https://github.com/toeverything/affine/edit/canary/.github/CLA.md
+[contributor license agreement]: https://cla-assistant.io/toeverything/AFFiNE
 [stars-icon]: https://img.shields.io/github/stars/toeverything/AFFiNE.svg?style=flat&logo=github&colorB=red&label=stars
 [codecov]: https://codecov.io/gh/toeverything/affine/branch/canary/graphs/badge.svg?branch=canary
-[node-version-icon]: https://img.shields.io/badge/node-%3E=18.16.1-success
 [typescript-version-icon]: https://img.shields.io/github/package-json/dependency-version/toeverything/affine/dev/typescript
 [react-version-icon]: https://img.shields.io/github/package-json/dependency-version/toeverything/AFFiNE/react?filename=packages%2Ffrontend%2Fcore%2Fpackage.json&color=rgb(97%2C228%2C251)
 [blocksuite-icon]: https://img.shields.io/github/package-json/dependency-version/toeverything/AFFiNE/@blocksuite/store?color=6880ff&filename=packages%2Ffrontend%2Fcore%2Fpackage.json&label=blocksuite