Fix typo in spec description

ee/spec/frontend/vue_shared/security_reports/components/vulnerability_detail_section_spec.js

@@ -56,7 +56,7 @@ describe('VulnerabilityDetails component', () => {
       expect(findCodeBlock().exists()).toBe(true);
     });
 
-    it('should display content in plain text', () => {
+    it('should not display content in plain text', () => {
       createComponent();
       expect(findPlainContent().exists()).toBe(false);
     });