Add structure

Author: pwseg

src/segment-app/extensions/dbt.md

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+---
+title: dbt Integration
+---

src/segment-app/extensions/git.md

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+---
+title: Git Sync Integration
+---

src/segment-app/extensions/index.md

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+---
+title: Extensions
+---
+
+Extensions integrate third-party tools into your existing Segment Workspace to help you automate tasks. Using Extensions, you can sync models with dbt labs and manage versioning for Segment Workspace changes using GitHub repositories.
+
+> info ""
+> Extensions is currently in public beta and is governed by Segment's [First Access and Beta Preview Terms](https://www.twilio.com/en-us/legal/tos){:target="_blank"}.