Change default image download URL in README

Updated the default image download URL in the README.

Author: kvinwang

verifier/README.md

@@ -61,13 +61,14 @@ Health check endpoint that returns service status.
 ```
 
 ## Configuration
+You usually don't need to edit the config file. Just using the default is fine, unless you need to deploy your cunstomized os images.
 
 ### Configuration Options
 
 - `host`: Server bind address (default: "0.0.0.0")
 - `port`: Server port (default: 8080)
 - `image_cache_dir`: Directory for cached OS images (default: "/tmp/dstack-verifier/cache")
-- `image_download_url`: URL template for downloading OS images (default: GitHub releases URL)
+- `image_download_url`: URL template for downloading OS images (default: Dstack official releases URL)
 - `image_download_timeout_secs`: Download timeout in seconds (default: 300)
 - `pccs_url`: Optional PCCS URL for quote verification
 
@@ -77,7 +78,7 @@ Health check endpoint that returns service status.
 host = "0.0.0.0"
 port = 8080
 image_cache_dir = "/tmp/dstack-verifier/cache"
-image_download_url = "http://0.0.0.0:8000/mr_{OS_IMAGE_HASH}.tar.gz"
+image_download_url = "https://download.dstack.org/os-images/mr_{OS_IMAGE_HASH}.tar.gz"
 image_download_timeout_secs = 300
 pccs_url = "https://pccs.phala.network"
 ```