Use correct env var, update comments

Author: korlaxxalrok

.env.example

@@ -15,8 +15,9 @@ DEBUG='True'
 # Sentry
 # Modify the Sentry config here. A DSN string is the minimum. Check the
 # application's Sentry init section and the Sentry documentation for the
-# defaults and options that may be set.
-DSN=''
+# defaults and options that may be set. If you don't want to use Sentry you can
+# leave this as is.
+#SENTRY_DSN=''
 
 # Add the following to your local .env file. They will be used in the CI process
 # and you can largely forget about them, but including them in your .env file