Update deploy-environment-variables.mdx (#1509)

base64 with -i for input file

Author: nilooy

docs/deploy-environment-variables.mdx

@@ -191,7 +191,7 @@ Securely pass a Google credential JSON file to your Trigger.dev task using envir
 In your terminal, run the following command and copy the resulting base64 string:
 
 ```
-base64 path/to/your/service-account-file.json
+base64 -i path/to/your/service-account-file.json
 ```
 
 </Step>