Fix color of static page links in high contrast theme (#10028)

app/javascript/styles/contrast/diff.scss

@@ -13,6 +13,10 @@
   }
 }
 
+.rich-formatting a,
+.rich-formatting p a,
+.rich-formatting li a,
+.landing-page__short-description p a,
 .status__content a,
 .reply-indicator__content a {
   color: lighten($ui-highlight-color, 12%);