Add comment to .env.example

.env.example

@@ -16,6 +16,8 @@ DATABASE_URL="postgresql://postgres:postgres@localhost:5432/openpipe?schema=publ
 # OpenAI API key. Instructions on generating a key can be found here:
 # https://help.openai.com/en/articles/4936850-where-do-i-find-my-secret-api-key
 OPENAI_API_KEY=""
+
+# Replicate API token. Create a token here: https://replicate.com/account/api-tokens
 REPLICATE_API_TOKEN=""
 
 NEXT_PUBLIC_SOCKET_URL="http://localhost:3318"