docs: add actor permission level env var

Author: stepskop

sources/platform/actors/development/programming_interface/environment_variables.md

@@ -53,6 +53,7 @@ Here's a table of key system environment variables:
 | `APIFY_HEADLESS` | If **1**, web browsers inside the Actor should run in headless mode (no windowing system available). |
 | `APIFY_IS_AT_HOME` | Contains **1** if the Actor is running on Apify servers. |
 | `ACTOR_MEMORY_MBYTES` | Size of memory allocated for the Actor run, in megabytes. Can be used to optimize memory usage or finetuning of low-level external libraries. |
+| `ACTOR_PERMISSION_LEVEL` | Permission level of the Actor (`LIMITED_PERMISSIONS` or `FULL_PERMISSIONS`). |
 | `APIFY_PROXY_PASSWORD` | Password for accessing Apify Proxy services. This password enables the Actor to utilize proxy servers on behalf of the user who initiated the Actor run. |
 | `APIFY_PROXY_PORT` | TCP port number to be used for connecting to the Apify Proxy. |
 | `APIFY_PROXY_STATUS_URL` | URL for retrieving proxy status information. Appending `?format=json` to this URL returns the data in JSON format for programmatic processing. |