Just ignore .env.production, avoid to effect for .env.example

https://github.com/github/gitignore/pull/3651/files#r576363678

Node.gitignore

@@ -70,7 +70,8 @@ web_modules/
 
 # dotenv environment variables file
 .env
-.env.*
+.env.test
+.env.production
 
 # parcel-bundler cache (https://parceljs.org/)
 .cache