chore: Add event attachments to README.md

Add the attachment feature to the readme
#4251

Signed-off-by: strobeflash <68517177+strobeflash@users.noreply.github.com>

README.md

@@ -23,9 +23,9 @@
 * :ballot_box_with_check: **Tasks!** See tasks or Deck cards with a due date directly in the calendar
 * :speaker: **Talk rooms!** Create an associated Talk room when booking a meeting with just one click
 * :calendar: **Appointment booking** Send people a link so they can book an appointment with you [using this app](https://apps.nextcloud.com/apps/appointments)
+* :paperclip: **Attachments!** Add, upload and view event attachments
 * :see_no_evil: **We’re not reinventing the wheel!** Based on the great [c-dav library](https://github.com/nextcloud/cdav-library), [ical.js](https://github.com/mozilla-comm/ical.js) and [fullcalendar](https://github.com/fullcalendar/fullcalendar) libraries.
 
-
 ## :hammer_and_wrench: Installation
 
 The app is distributed through the [app store](https://apps.nextcloud.com/apps/calendar) and you can install it [right from your Nextcloud installation](https://docs.nextcloud.com/server/stable/admin_manual/apps_management.html).