add extensions docs

Author: forstisabella

src/connections/reverse-etl/reverse-etl-source-setup-guides/bigquery-setup.md

@@ -30,6 +30,9 @@ To set up the Segment BigQuery connector:
 
 After you've added BigQuery as a source, you can [add a model](/docs/connections/reverse-etl#step-2-add-a-model).
 
+> info "BigQuery Reverse ETL sources support Segment's dbt extension"
+> If you have an existing dbt account with a Git repository, you can use [Segment's dbt extension](/docs/segment-app/extensions/dbt/) to centralize model management and versioning, reduce redundancies, and run CI checks to prevent breaking changes.
+
 ## Constructing your own role or policy
 When you construct your own role or policy, Segment needs the following permissions:
 

src/connections/reverse-etl/reverse-etl-source-setup-guides/databricks-setup.md

@@ -4,11 +4,10 @@ title: Databricks Reverse ETL Setup
 
 Set up Databricks as your Reverse ETL source. 
 
-At a high level, when you set up Databricks for Reverse ETL, the configured service-principal needs read permissions for any resources (databases, schemas, tables) the query needs to access. Segment keeps track of changes to your query results with a managed schema (`__SEGMENT_REVERSE_ETL`), which requires the configured service-principal to allow write permissions for that schema.
-
-> info ""
-> Segment supports only OAuth (M2M) authentication. To generate a client ID and Secret, follow the steps listed in Databricks' [OAuth machine-to-machine (M2M) authentication](https://docs.databricks.com/en/dev-tools/auth/oauth-m2m.html){:target="_blank"} documentation.
+At a high level, when you set up Databricks for Reverse ETL, the configured service-principal needs read permissions for any resources (databases, schemas, tables) the query needs to access. Segment keeps track of changes to your query results with a managed schema (`__SEGMENT_REVERSE_ETL`), which requires the configured service-principal to allow write permissions for that schema. Segment supports only OAuth (M2M) authentication. To generate a client ID and Secret, follow the steps listed in Databricks' [OAuth machine-to-machine (M2M) authentication](https://docs.databricks.com/en/dev-tools/auth/oauth-m2m.html){:target="_blank"} documentation.
 
+> info "Databricks Reverse ETL sources support Segment's dbt extension"
+> If you have an existing dbt account with a Git repository, you can use [Segment's dbt extension](/docs/segment-app/extensions/dbt/) to centralize model management and versioning, reduce redundancies, and run CI checks to prevent breaking changes.
 
 ## Required permissions
 * Make sure the service principal you use to connect to Segment has permissions to use that warehouse. In the Databricks console go to **SQL warehouses** and select the warehouse you're using. Navigate to **Overview > Permissions** and make sure the service principal you use to connect to Segment has *can use* permissions.

src/connections/reverse-etl/reverse-etl-source-setup-guides/postgres-setup.md

@@ -6,6 +6,9 @@ Set up Postgres as your Reverse ETL source.
 
 At a high level, when you set up Postgres for Reverse ETL, the configured user/role needs read permissions for any resources (databases, schemas, tables) the query needs to access. Segment keeps track of changes to your query results with a managed schema (`__SEGMENT_REVERSE_ETL`), which requires the configured user to allow write permissions for that schema.
 
+> info "Postgres Reverse ETL sources support Segment's dbt extension"
+> If you have an existing dbt account with a Git repository, you can use [Segment's dbt extension](/docs/segment-app/extensions/dbt/) to centralize model management and versioning, reduce redundancies, and run CI checks to prevent breaking changes.
+
 Segment supports the following Postgres database providers:
 - Heroku
 - RDS

src/connections/reverse-etl/reverse-etl-source-setup-guides/redshift-setup.md

@@ -5,7 +5,10 @@ redirect_from:
   - '/reverse-etl/redshift-setup/'
 ---
 
-Set up Redshift as your Reverse ETL source. 
+Set up Redshift as your Reverse ETL source.
+
+> info "Redshift Reverse ETL sources support Segment's dbt extension"
+> If you have an existing dbt account with a Git repository, you can use [Segment's dbt extension](/docs/segment-app/extensions/dbt/) to centralize model management and versioning, reduce redundancies, and run CI checks to prevent breaking changes.
 
 To set up Redshift with Reverse ETL: 
 1. Log in to Redshift and select the Redshift cluster you want to connect with Reverse ETL.

src/connections/reverse-etl/system.md

@@ -5,6 +5,18 @@ beta: false
 
 View reference information about how Segment detects data changes in your warehouse and the rate and usage limits associated with Reverse ETL. 
 
+## Extensions
+
+Extensions integrate third-party tools into your existing Segment workspace to help you automate tasks.
+
+> info ""
+> Extensions is currently in public beta and is governed by Segment’s First Access and Beta Preview Terms. During Public Beta, Extensions is available for Team and Developer plans only. Reach out to Segment if you’re on a Business Tier plan and would like to participate in the Public Beta.
+
+Segment has two extensions that you can use to manage your Reverse ETL sources:
+
+- [dbt models and dbt Cloud](/docs/segment-app/extensions/dbt/): Sync your Reverse ETL models with dbt labs models and syncs to help centralize model management and versioning, reduce redundancies, and run CI checks to prevent breaking changes.
+- [Git sync](/docs/segment-app/extensions/git/): Manage versioning by syncing changes you make to your Reverse ETL sources from your Segment workspace to a Git repository.
+
 ## Record diffing
 Reverse ETL computes the incremental changes to your data directly within your data warehouse. The Unique Identifier column is used to detect the data changes, such as new, updated, and deleted records.