Fix documentation for navbar-item-hover-color's default value (#1578)

docs/_data/variables/components/navbar.json

@@ -24,7 +24,7 @@
     "navbar-item-hover-color": {
       "id": "navbar-item-hover-color",
       "name": "$navbar-item-hover-color",
-      "value": "$black"
+      "value": "$link"
     },
     "navbar-item-hover-background-color": {
       "id": "navbar-item-hover-background-color",