UI: add enterkeyhint end into the MessageComposer

src/platform/web/ui/session/room/MessageComposer.js

@@ -28,6 +28,7 @@ export class MessageComposer extends TemplateView {
     render(t, vm) {
         this._input = t.input({
             placeholder: vm.isEncrypted ? "Send an encrypted message…" : "Send a message…",
+            enterkeyhint: 'send',
             onKeydown: e => this._onKeyDown(e),
             onInput: () => vm.setInput(this._input.value),
         });