Update supabase-js v2 setSession() example

[Aerilym]

Improve documentation

https://supabase.com/docs/reference/javascript/auth-setsession

Describe the problem

The example given is inaccurate and doesn't work with the current version of supabase-js. This has been discussed and mentioned in:
gotrue-js PR473
gitrue-js PR511

Describe the improvement

Update the example to use the refresh token and access token in an object.

supabase.auth.setSession({
      refresh_token
      access_token
    });