Add documentation around Snowflake Enterprise-only source table and downstream models

[aleix-cd]

Hi there!

Just realised, after a few months of using this package, that we had a long running model (stg_access_history) taking around 5-6min to build on average, and which did not had any records in it.

This model is based on the snowflake.account_usage.access_history table, which is only populated for Snowflake Enterprise accounts.

I think it would be helpful for people to mention this somewhere in the package docs.

E.g.

If you are not part of a Snowflake Enterprise account, disable the following models since their source table will be empty:
- `stg_access_history`
- `query_base_object_access`
- `query_direct_object_access`
- `query_base_table_access`
- `query_direct_table_access`