Fix typo for dismissible

Fix a typo to make the content editor feedback issue popup
non dismissible.

Changelog: fixed

app/assets/javascripts/pages/shared/wikis/components/wiki_form.vue

@@ -461,7 +461,7 @@ export default {
         </markdown-field>
 
         <div v-if="isContentEditorActive">
-          <gl-alert class="gl-mb-6" variant="tip" :dismissable="false">
+          <gl-alert class="gl-mb-6" variant="tip" :dismissible="false">
             <gl-sprintf :message="$options.i18n.contentEditor.feedbackTip">
               <template
                 #link="// eslint-disable-next-line vue/no-template-shadow