Yes, that is the correct approach.
You could also reduce it to a single line, as such:
@reboot /root/website1/starter.sh && /root/website2/starter.sh
Just keep in mind that the scripts will run consecutively (not concurrently), and the second script will only run if the first script/command exits successfully. If the second script should run regardless of the result of the previous script, separate the commands with a semi-colon instead of &&.
If you need the scripts to run in parallel, you should stick with your original approach (one command/script on each line).
The double-ampersand (&&) can also be used in the "command" section to run multiple commands consecutively, but only if the previous command exits successfully. A string of commands joined by the double-ampersand will only get to the last command if all the previous commands are run successfully. If exit error-checking is not of a concern, string commands together, separated with a semi-colon (;)
CronHowto - Crontab Example