docs: add docs for the ledger identifier property in the keys.json file

docs/advanced_reference/commands/autonomy_deploy.md

@@ -114,6 +114,20 @@ autonomy deploy build keys.json -ltm
 
 Builds a service deployment using the keys stored in the file `keys.json` and applying environment variables to the service configuration file. The deployment will be generated by default for as many agents as keys are stored in `keys.json`. By default, the command searches for the file `keys.json`, if no file name is provided.
 
+If you are manually defining `keys.json` make sure to include `ledger` property for a key object. This will be used when writing key files to the deployment environment. If you don't specify the property `ethereum` will be used as default ledger identifier, so if you're running an agent against a different ledger (eg. `solana`) you'll have to specify this property manually like this
+
+```json
+[
+    {
+        "address": "Solanaaddress",
+        "private_key": "Solanaprivatekey",
+        "ledger": "solana"
+    }
+]
+```
+
+If the keys are generated using `autonomy generate-key` command the `ledger` property will be included automatically.
+
 ### Private key security
 
 When building deployments, you can use password protected privates keys (eg. generated using `autonomy generate-key LEDGER --password PASSWORD`) to avoid exposing them.