doc: adjust TOC margins

PR-URL: nodejs#28075
Reviewed-By: Rich Trott <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Trivikram Kamat <[email protected]>
Reviewed-By: Yongsheng Zhang <[email protected]>

Author: Roman Reiss

doc/api_assets/style.css

@@ -353,10 +353,13 @@ hr {
 
 #toc h2 {
   margin-top: 0;
-  line-height: 0;
   margin: 1.5rem 0;
 }
 
+#toc p {
+  margin: 0;
+}
+
 #toc ul a {
   text-decoration:none;
 }