Update additional-configuration.adoc to mention access mode annotation.

Signed-off-by: Angel Misevski <[email protected]>

docs/additional-configuration.adoc

@@ -117,6 +117,7 @@ By default, resources will be mounted based on the resource name:
 Mounting resources can be additionally configured via **annotations**:
 
 * `controller.devfile.io/mount-path`: configure where the resource should be mounted
+* `controller.devfile.io/mount-access-mode`: for secrets and configmaps only, configure file permissions on files mounted from this configmap/secret. Permissions can be specified in decimal (e.g. `"512"`) or octal notation by prefixing with a "0" (e.g. `"0777"`)
 * `controller.devfile.io/mount-as`: for secrets and configmaps only, configure how the resource should be mounted to the workspace
 +
 --