Updated Using Oracle Cloud Infrastructure DNS (markdown)

How-to-use-Oracle-Cloud-Infrastructure-DNS.md

@@ -9,15 +9,29 @@ Before you can use OCI DNS with `acme.sh`, you'll need  the following:
 * The [tenancy and service account OCIDs][OCIDS]
 
 We recommend [installing the OCI CLI][CLI] and using the [interactive setup process][CSTP]
-to create an API signing keypair.
+to create an API signing keypair. If the OCI CLI is configured, the plugin will automatically
+detect and use the configuration file for authentication. 
 
 Alternatively, the [OCI Developer Guide][DG] provides the manual steps required
 to generate the API signing keys and determine the required OCIDs.
 
-## Configuring the `dns_oci` plugin
+## Configuration
 
-To use the `dns_oci` plugin, the following environment variables must be
-configured:
+### Automatic configuration
+
+**No configuration is required** if the [OCI CLI][CLI] is installed with its configuraton file 
+located at `$HOME/.oci/config` and uses the `DEFAULT` profile.
+
+If necessary,  you can overrride either the default configuration file path or profile
+using the following two environment variables:
+
+* `OCI_CLI_CONFIG_FILE`: set to the full path including filename of the OCI SDK and CLI 
+  configuration file. 
+* `OCI_CLI_PROFILE`: provide an existing profile from the configuration file. Case-sensitive!
+
+### Manual configuration
+
+If the OCI CLI is not installed, the following environment variables must be set:
 
 * `OCI_CLI_USER`: OCID of the user calling the API. Example: `ocid1.user.oc1..<unique_ID>`
 * `OCI_CLI_TENANCY`: OCID of your tenancy. Example: `ocid1.tenancy.oc1..<unique_ID>`
@@ -30,6 +44,9 @@ following two variables:
   in PEM format; or
 * `OCI_CLI_KEY`: the private API signing key in PEM format
 
+> **Tip:** The variables above can also be used to override the values stored in the 
+> OCI SDK and CLI configuration file.
+
 ### Issuing a certificate
 
 To issue a certificate, ensure either the OCI CLI is working correctly or all