Update notify documentation.

Author: brenns10

src/jupyter_contrib_nbextensions/nbextensions/notify/notify.yaml

@@ -13,6 +13,6 @@ Parameters:
   input_type: checkbox
   default: false
 - name: notify.play_sound
-  description: Play notification sound. (Not yet supported in browsers)
+  description: Play notification sound.
   input_type: checkbox
   default: false

src/jupyter_contrib_nbextensions/nbextensions/notify/readme.md

@@ -20,9 +20,7 @@ You may configure the plugin so that notifications require manual dismissal
 before disappearing. Browser support is limited, see
 [here](https://developer.mozilla.org/en-US/docs/Web/API/notification/requireInteraction)
 to check if your browser supports this. You may also configure the plugin so
-that notifications play a sound, although this is currently
-[unsupported](https://developer.mozilla.org/en-US/docs/Web/API/notification/sound)
-in all major browsers.
+that notifications play a sound.
 
 ![notification](notification.png "notification")