Add custom views docs (#1732)

Add docs for custom views methods. This code has been in the library for quite a while but we had not added to the documentation yet.

Author: bcantoni

_includes/docs_menu.html

@@ -44,7 +44,10 @@
                     <a href="{{ site.baseurl }}/docs/api-ref#connections">Connections</a>
                 </li>
                 <li>
-                    <a href="{{ site.baseurl }}/docs/api-ref#data-sources">Data sources</a>
+                    <a href="{{ site.baseurl }}/docs/api-ref#custom-views">Custom Views</a>
+                </li>
+                <li>
+                    <a href="{{ site.baseurl }}/docs/api-ref#data-sources">Data Sources</a>
                 </li>
                 <li>
                     <a href="{{ site.baseurl }}/docs/api-ref#filters">Filters</a>
@@ -84,6 +87,7 @@
                 </li>
                 <li>
                     <a href="{{ site.baseurl }}/docs/api-ref#views">Views</a>
+                </li>
                 <li>
                     <a href="{{ site.baseurl }}/docs/api-ref#webhooks">Webhooks</a>
                 </li>