Update README with the new API

[nikeshnaik]

Describe the bug
In the ReadMe.md file, the examples shown for inserting data, selecting data from the countries table returns class object, an assertion on that object to get data is throwing error. Is doc outdated?

To Reproduce
Steps to reproduce the behaviour:
Run the examples shown in ReadMe.md

assert len(data.get("data", [])) > 0 AttributeError: 'APIResponse' object has no attribute 'get'

Expected behaviour
`supabase: Client = create_client(url, key)
data = supabase.table("countries").select("*").execute()
Assert we pulled real data.
assert len(data.get("data", [])) > 0 ----> Throwing error

supabase: Client = create_client(url, key)
data = supabase.table("countries").select("*").execute()
Assert we pulled real data.
assert len(data.data) > 0` --> This fixes it, shall I update remaining examples.

[dreinon]

Yet to be updated! Forgot to update it, sorry