documentation update for private key password

Author: varmax2511

website/docs/index.html.markdown

@@ -66,6 +66,7 @@ sufficient. For more complex environments you may want to maintain multiple sets
 See the [compute single instance example](https://github.com/oracle/terraform-provider-oci/tree/master/examples/compute/instance) for more info.
 
 In your `~/.bash_profile` set these variables:
+
 ```
 export TF_VAR_tenancy_ocid=<value>
 export TF_VAR_compartment_ocid=<value>
@@ -97,7 +98,7 @@ The variables won't be set for the current session, exit the terminal and reopen
 It is possible to define the required provider values in the same `~/.oci/config` file that the SDKs and CLI support. 
 For details on setting up this configuration see [SDK and CLI Configuration File](https://docs.cloud.oracle.com/iaas/Content/API/Concepts/sdkconfig.htm).  
 
-_Note: only the `[default]` profile is supported, and the parameter names are slightly different. Provider block from terraform config can be completely removed if all API Key based authentication required values are provided as environment variables, in a `*.tfvars file` or `~/.oci/config`_
+_Note: only the `[default]` profile is supported, and the parameter names are slightly different. Provider block from terraform config can be completely removed if all API Key based authentication required values are provided as environment variables, in a `*.tfvars file` or `~/.oci/config`_. When using empty provider block, `private_key_password` if required should to be set in `~/.oci/config`. 
 
 ### Instance Principal Authentication
 Instance Principal authentication allows you to run Terraform from an OCI Instance within your Tenancy. To enable Instance