chore: explain account-id config in README

README.md

@@ -6,14 +6,16 @@ Maxmind's GeoLite2 Free Databases download helper.
 
 ### Access Key
 
-**IMPORTANT** You must setup `MAXMIND_LICENSE_KEY` environment variable be able to download databases. To do so, go to the https://www.maxmind.com/en/geolite2/signup, create a free account and generate new license key.
+**IMPORTANT** You must set up `MAXMIND_ACCOUNT_ID` and `MAXMIND_LICENSE_KEY` environment variables to be able to download databases. To do so, go to the https://www.maxmind.com/en/geolite2/signup, create a free account and generate new license key.
 
-If you don't have access to the environment variables during installation, you can provide license key via `package.json`:
+If you don't have access to the environment variables during installation, you can provide config via `package.json`:
 
 ```jsonc
 {
   ...
   "geolite2": {
+    // specify the account id
+    "account-id": "<your account id>",
     // specify the key
     "license-key": "<your license key>",
     // ... or specify the file where key is located: