inscrease space between API entries

Author: rmorshea

docs/source/_static/css/larger-api-margins.css

@@ -0,0 +1,7 @@
+:is(.data, .function, .class, .exception).py {
+  margin-top: 3em;
+}
+
+:is(.attribute, .method).py {
+  margin-top: 1.8em;
+}