changed accounts_id to required (#3244)

* changed accounts_id to required

* changed accounts_id to optional/required

Author: jiropardo

docs/index.md

@@ -209,7 +209,7 @@ Alternatively, you can provide this value as an environment variable `DATABRICKS
 * `config_file` - (optional) Location of the Databricks CLI credentials file created by `databricks configure --token` command (~/.databrickscfg by default). Check [Databricks CLI documentation](https://docs.databricks.com/dev-tools/cli/index.html#set-up-authentication) for more details. The provider uses configuration file credentials when you don't specify host/token/username/password/azure attributes. Alternatively, you can provide this value as an environment variable `DATABRICKS_CONFIG_FILE`. This field defaults to `~/.databrickscfg`.
 * `profile` - (optional) Connection profile specified within ~/.databrickscfg. Please check [connection profiles section](https://docs.databricks.com/dev-tools/cli/index.html#connection-profiles) for more details. This field defaults to
 `DEFAULT`.
-* `account_id` - (optional) Account Id that could be found in the top right corner of [Accounts Console](https://accounts.cloud.databricks.com/). Alternatively, you can provide this value as an environment variable `DATABRICKS_ACCOUNT_ID`. Only has effect when `host = "https://accounts.cloud.databricks.com/"`, and is currently used to provision account admins via [databricks_user](resources/user.md). In the future releases of the provider this property will also be used specify account for `databricks_mws_*` resources as well.
+* `account_id` - (optional for workspace-level operations, but required for account-level) Account Id that could be found in the top right corner of [Accounts Console](https://accounts.cloud.databricks.com/). Alternatively, you can provide this value as an environment variable `DATABRICKS_ACCOUNT_ID`. Only has effect when `host = "https://accounts.cloud.databricks.com/"`, and is currently used to provision account admins via [databricks_user](resources/user.md). In the future releases of the provider this property will also be used specify account for `databricks_mws_*` resources as well. 
 * `auth_type` - (optional) enforce specific auth type to be used in very rare cases, where a single Terraform state manages Databricks workspaces on more than one cloud and `more than one authorization method configured` error is a false positive. Valid values are `pat`, `basic`, `oauth-m2m`, `azure-client-secret`, `azure-msi`, `azure-cli`, `google-credentials`, and `google-id`.
 
 ## Special configurations for AWS