Update snowflake-permissions.md (#3774)

## What are you changing in this pull request and why?
Without the monitor permissions, dbt fails with permission errors. I am
not 100% sure exactly what part of my dbt script causes the issue, and
it seems to only occur in on-run-start and on-run-end hooks, but without
these the runs are not succesful.

## Checklist
- [x] Review the [Content style
guide](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/content-style-guide.md)
and [About
versioning](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#adding-a-new-version)
so my content adheres to these guidelines.
- [x] Add a checklist item for anything that needs to happen before this
PR is merged, such as "needs technical review" or "change base branch."

website/docs/reference/snowflake-permissions.md

@@ -15,9 +15,11 @@ grant usage on schema database.an_existing_schema to role role_name;
 grant create table on schema database.an_existing_schema to role role_name;
 grant create view on schema database.an_existing_schema to role role_name;
 grant usage on future schemas in database database_name to role role_name;
+grant monitor on future schemas in database database_name to role role_name;
 grant select on future tables in database database_name to role role_name;
 grant select on future views in database database_name to role role_name;
 grant usage on all schemas in database database_name to role role_name;
+grant monitor on all schemas in database database_name to role role_name;
 grant select on all tables in database database_name to role role_name;
 grant select on all views in database database_name to role role_name;
 ```