docs/content: Self-close children field

Currently docs pipeline is failing due to a failed to extract shortcode error
as the shortcode "children" must be closed or self-closed.

Add self-closing to the docs field

Change-Id: Iea7b61a0a4dc19a930d761e19fc321f2953b46a0

docs/content/clients/_index.md

@@ -8,4 +8,4 @@ Clients are generated from the base `.proto` files shipped in this repository us
 
 While Arista maintains clients for some languages, creating a client for your language of choice is also possible.
 
-{{% children  %}}
+{{% children  /%}}