Update reference to renamed font style. (swiftlang#683)

Resolves: rdar://110085109

Author: mportiz08

src/components/ContentNode/Caption.vue

@@ -44,7 +44,7 @@ export default {
 @import 'docc-render/styles/_core.scss';
 
 .caption {
-  @include font-styles(documentation-figcaption);
+  @include font-styles(documentation-caption);
 
   &:last-child {
     margin-top: var(--spacing-stacked-margin-large);