Update documentation on TypeScript-bindings.

Author: josteink

README.md

@@ -779,6 +779,7 @@ gmail.observe.on('view_email', function(obj) {
 
  - **load** - When the gmail interface has completed loading
  - **compose** - When a new compose window opens, or a message is replied to or forwarded
+ - **compose_cancelled** - When an existing compose window is closed.
  - **recipient_change** - When the recipient (to, cc or bcc) is changed when composing a new email or replying/forwarding an email
  - **view_thread** - When a new coversation thread is opened
   - **view_thread Sub-observers**

src/gmail.d.ts

@@ -615,7 +615,8 @@ declare type GmailBindAction =
     | 'add_to_tasks' | 'move_label' | 'save_draft' | 'discard_draft' | 'send_message'
     | 'expand_categories' | 'delete_label' | 'show_newly_arrived_message' | 'poll'
     | 'new_email' | 'refresh' | 'open_email' | 'upload_attachment' | 'compose'
-    | 'recipient_change' | 'view_thread' | 'view_email' | 'load_email_menu';
+    | 'compose_cancelled' | 'recipient_change' | 'view_thread' | 'view_email'
+    | 'load_email_menu';
 
 interface GmailObserve {
     /**