docs: Update feature tutorial for server_events_dispatch.js.

docs/new-feature-tutorial.md

@@ -60,7 +60,7 @@ Realm setting, in `test_realm.py`).
 **JavaScript:** Zulip's JavaScript is located in the directory
 `static/js/`. The exact files you may need to change depend on your
 feature. If you've added a new event that is sent to clients, be sure to
-add a handler for it to `static/js/server_events.js`.
+add a handler for it to `static/js/server_events_dispatch.js`.
 
 **CSS:** The primary CSS file is `static/styles/zulip.css`. If your new
 feature requires UI changes, you may need to add additional CSS to this
@@ -395,10 +395,10 @@ form control in `static/js/admin.js`.
       }
     });
 
-Finally, update `server_events.js` to handle related events coming from
+Finally, update `server_events_dispatch.js` to handle related events coming from
 the server.
 
-    # static/js/server_events.js
+    # static/js/server_events_dispatch.js
 
     function dispatch_normal_event(event) {
         switch (event.type) {

static/js/server_events.js

@@ -59,6 +59,10 @@ function get_events_success(events) {
         events_stored_while_loading = [];
     }
 
+    // Most events are dispatched via the code server_events_dispatch,
+    // called in the default case.  The goal of this split is to avoid
+    // contributors needing to read or understand the complex and
+    // rarely modified logic for non-normal events.
     var dispatch_event = function dispatch_event(event) {
         switch (event.type) {
         case 'message':