fix image tag locking example

Author: nicktrn

hosting/docker/.env.example

@@ -29,7 +29,7 @@ DIRECT_URL=postgresql://postgres:unsafe-postgres-pw@postgres:5432/main?schema=pu
 
 # Trigger image tag
 # - This is the version of the webapp and worker images to use, they should be locked to a specific version in production
-# - For example: TRIGGER_IMAGE_TAG=v4-beta.21
+# - For example: TRIGGER_IMAGE_TAG=v4.0.0-v4-beta.21
 TRIGGER_IMAGE_TAG=v4-beta
 
 # Webapp