README.md in mailersend-ruby-0.2.5 vs README.md in mailersend-ruby-1.0.0

@@ -68,10 +68,10 @@
 
 You will have to initalize it in your Ruby file with `require "mailersend-ruby"`.
 
 # Usage
 
-This SDK requires that you either have `.env` file with `API_TOKEN` env variable or that your variable is enabled system wide (useful for Docker/Kubernetes). The example of how `API_TOKEN` should look like is in `.env.example`.
+This SDK requires that you either have `.env` file with `MAILERSEND_API_TOKEN` env variable or that your variable is enabled system wide (useful for Docker/Kubernetes). The example of how `MAILERSEND_API_TOKEN` should look like is in `.env.example`.
 
 ## Email
 
 ### Send an email