Added information related to using the Environment variables in AHK

Custom-Post-Processing-Scripts.md

@@ -111,4 +111,9 @@ Key points:
  - `import\copy` must be `no` to prevent beets moving files
  - You should configure beets file naming to match your lidarr file naming to avoid nasty surprises
  - You must set `BEET_CONFIG` to point to your beets config file in `beet_import.sh`
- - You should trigger the custom script on Album Import.
+ - You should trigger the custom script on Album Import.
+
+#### AHK ####
+To use the environment variables in AHK you can use the EnvGet command, Here are some examples:
+EnvGet, EventType, lidarr_eventtype
+EnvGet, MusicFolder, lidarr_artist_path