feat: update readme for web-sdk (#203)

* feat: update readme for web-sdk

Explain work in progress passkey, current local setup

* Update packages/sdk-platforms/web/README.md

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

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Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: cpb8010