Update UserGuide.md

Author: Lingy12

docs/UserGuide.md

@@ -110,7 +110,7 @@ A journal entry can have any number of contacts or tags (including 0)
 Examples:
 * `addj n/Meeting with client` Adds a journal entry with the name
 `Meeting with client`.
-* `addj n/Meeting with client at/2020-9-20 1400 d/Tea` Adds a journal
+* `addj n/Meeting with client at/2020-9-20 14:00 d/Tea` Adds a journal
 entry with the name `Meeting with client`, a date and time of `2020-9-20 14:00`
 and content `Tea`.