leave: add page (#1574)

pages/common/leave.md

@@ -0,0 +1,20 @@
+# leave
+
+> Remind when it's time to leave.
+> To remove reminders use `kill $(pidof leave)`.
+
+- Set a reminder at a given time:
+
+`leave {{time_to_leave}}`
+
+- Remind to leave at noon:
+
+`leave {{1200}}`
+
+- Set a reminder in a specific amount of time:
+
+`leave +{{amount_of_time}}`
+
+- Remind to leave in 4 hours and 4 minutes:
+
+`leave +{{0404}}`