fix typo in quickstart

doc/quickstart.md

@@ -55,14 +55,14 @@ currently in and run `comitium add` for each of them.
 
 I just put it in my crontab to refresh on a six hour interval:
 ```
-* */6 * * * /usr/local/bin/comitium refresh
+0 */6 * * * /usr/local/bin/comitium refresh
 ```
 
 If you set the data directory with an environment variable like mentioned
 earlier, make sure to do something like this, because the environment variable
 isn't passed to cron:
 ```
-* */6 * * * /usr/local/bin/comitium refresh -d /home/somebody/public_gemini
+0 */6 * * * /usr/local/bin/comitium refresh -d /home/somebody/public_gemini
 ```