Fix Markdown not rendering on releases page

Previously Markdown that appeared in the releases page would only be
shown in the tags page but not in the summary page. We fix this by
adding a reference to GitLab Markdown in the description block and
ensuring the Vue component renders Markdown.

Closes https://gitlab.com/gitlab-org/gitlab/issues/39483

app/assets/javascripts/releases/list/components/release_block.vue

 <script>
 import _ from 'underscore';
+import $ from 'jquery';
 import { slugify } from '~/lib/utils/text_utility';
 import { getLocationHash } from '~/lib/utils/url_utility';
 import { scrollToElement } from '~/lib/utils/common_utils';
 import glFeatureFlagsMixin from '~/vue_shared/mixins/gl_feature_flags_mixin';
+import '~/behaviors/markdown/render_gfm';
 import EvidenceBlock from './evidence_block.vue';
 import ReleaseBlockAssets from './release_block_assets.vue';
 import ReleaseBlockFooter from './release_block_footer.vue';
@@ -65,7 +67,10 @@ export default {
       return Boolean(this.glFeatures.releaseIssueSummary && !_.isEmpty(this.release.milestones));
     },
   },
+
   mounted() {
+    this.renderGFM();
+
     const hash = getLocationHash();
     if (hash && slugify(hash) === this.id) {
       this.isHighlighted = true;
@@ -76,6 +81,11 @@ export default {
       scrollToElement(this.$el);
     }
   },
+  methods: {
+    renderGFM() {
+      $(this.$refs['gfm-content']).renderGFM();
+    },
+  },
 };
 </script>
 <template>
@@ -91,7 +101,7 @@ export default {
       <release-block-assets v-if="shouldRenderAssets" :assets="assets" />
       <evidence-block v-if="hasEvidence && shouldShowEvidence" :release="release" />
 
-      <div class="card-text prepend-top-default">
+      <div ref="gfm-content" class="card-text prepend-top-default">
         <div v-html="release.description_html"></div>
       </div>
     </div>

changelogs/unreleased/sh-fix-mermaid-releases-page.yml

+---
+title: Fix Markdown not rendering on releases page
+merge_request: 23370
+author:
+type: fixed

spec/frontend/releases/list/components/release_block_spec.js

+import $ from 'jquery';
 import { mount } from '@vue/test-utils';
 import { first } from 'underscore';
 import EvidenceBlock from '~/releases/list/components/evidence_block.vue';
@@ -43,6 +44,7 @@ describe('Release block', () => {
   const editButton = () => wrapper.find('.js-edit-button');
 
   beforeEach(() => {
+    jest.spyOn($.fn, 'renderGFM');
     releaseClone = JSON.parse(JSON.stringify(release));
   });
 
@@ -66,6 +68,11 @@ describe('Release block', () => {
       expect(wrapper.text()).toContain(release.name);
     });
 
+    it('renders release description', () => {
+      expect(wrapper.vm.$refs['gfm-content']).toBeDefined();
+      expect($.fn.renderGFM).toHaveBeenCalledTimes(1);
+    });
+
     it('renders release date', () => {
       expect(wrapper.text()).toContain(timeagoMixin.methods.timeFormatted(release.released_at));
     });