update non functional requirements

docs/DeveloperGuide.md

@@ -326,6 +326,9 @@ Priorities: High (must have) - `* * *`, Medium (nice to have) - `* *`, Low (unli
 1.  Should work on any _mainstream OS_ as long as it has Java `11` or above installed.
 2.  Should be able to hold up to 1000 persons without a noticeable sluggishness in performance for typical usage.
 3.  A user with above average typing speed for regular English text (i.e. not code, not system admin commands) should be able to accomplish most of the tasks faster using commands than using the mouse.
+4.  Should respond immediately to user input, as user will most likely be using a chain of commands
+5.  Should be able to use offline
+6.  The UI should be resizable as users will likely be referencing other tabs while using this product.
 
 *{More to be added}*