Merge pull request #1041 from tldr-pages/cron

cron: Add job definition example (addresses #822)

pages/common/crontab.md

@@ -1,6 +1,7 @@
 # crontab
 
 > Schedule cron jobs to run on a time interval for the current user.
+> Job definition format: "(min) (hour) (day_of_month) (month) (day_of_week) command_to_execute".
 
 - Edit the crontab file for the current user:
 
@@ -13,3 +14,15 @@
 - Remove all cron jobs for the current user:
 
 `crontab -r`
+
+- Sample job which runs at 10:00 every day. * means any value:
+
+`0 10 * * * {{path/to/script.sh}}`
+
+- Sample job which runs every minute on the 3rd of April:
+
+`* * 3 Apr * {{path/to/script.sh}}`
+
+- Sample job which runs at 02:30 every Friday:
+
+`30 2 * * Fri {{path/to/script.sh}}`