Missing RLS policy guide in demo readme.md

[DevDengChao]

When running the demo app locally, you need to fill the SUPABAS_URL and SUPABASE_KEY env variable in .env file, and create a table named tasks in the supabase project, but the demo/readme.md dosen't mentioned you have to disable the Row level security (RLS) function to make it works.

Steps to reproduce

1. create a test supabase project
2. fill the SUPABAS_URL and SUPABASE_KEY env variable
3. launch the app
4. login with your Github account
5. create a TODO and save it

What is Expected?

The demo/readme.md should guide developers to disable RLS or add a proper RLS policy to have a quick experience.

What is actually happening?

new row violates row-level security policy for table "tasks"