re-add sponsoring links

docs/index.md

@@ -20,8 +20,7 @@ For now, you can find the following here:
 * [Principles](rules.en.md)
 
 
-<!--
 The event would not be possible without some companies providing network hardware,
-cloud resources and connectivity services. Find them [here](sponsoring.md).
--->
+cloud resources and connectivity services. Find them 
+[here](https://infra.rc3.world/sponsoring.html).