Update apps/site/pages/en/learn/command-line/how-to-read-environment-variables-from-nodejs.md

Co-authored-by: Michael Esteban <mickel13@gmail.com>
Signed-off-by: YCM Jason <me@ycmjason.com>

Author: ycmjason

apps/site/pages/en/learn/command-line/how-to-read-environment-variables-from-nodejs.md

@@ -76,6 +76,7 @@ Because this method is invoked post-initialization, the setting of startup-relat
 ### Example
 
 ```txt
+// .env file
 PORT=1234
 ```