New page for date (display only)

Fix #15. Based on #32, thanks @shrayas.

common/date.md

@@ -0,0 +1,12 @@
+# date
+
+> Set or display the system date
+
+- Display the date using the default locale
+
+`date +"%c"`
+
+- Display the date using a custom format
+
+`date +"%d/%m/%Y %H:%M:%S"`
+