docs: add index page for cloud logging admin tools (googleapis#2414)

Add _index page for cloud logging admin tools for drop down.

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Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: Yuan325

docs/en/resources/tools/cloudloggingadmin/_index.md

@@ -0,0 +1,8 @@
+---
+title: "Cloud Logging Admin"
+linkTitle: "Cloud Logging Admin"
+type: docs
+weight: 1
+description: > 
+  Tools that work with Cloud Logging Admin Sources.
+---