feat: Add more context on data storage locations and API endpoints

Give more context on how/when to use our API base domains.

Refs #11058

Author: markstory

docs/api/index.mdx

@@ -20,3 +20,17 @@ Sentry's web API is **v0** and under development. Public endpoints, especially t
 - [Requests](/api/requests/)
 - [Tutorial: Create a Sentry Authentication Token](/api/guides/create-auth-token/)
 - [Tutorial: Create and List Teams with the Sentry API](/api/guides/teams-tutorial/)
+
+## Finding the API base domain
+
+While many of the API examples use `sentry.io` as the host for API endpoints, if
+you want to take advantage of [data storage location](https://docs.sentry.io/organization/data-storage-location/#what-types-of-data-are-stored-where) you should use the region
+specific domains instead.
+
+- US region is hosted on `us.sentry.io`
+- DE region is hosted on `de.sentry.io`.
+
+To find out which API resources are available on region base domains see [what
+types of data are stored
+where](https://docs.sentry.io/organization/data-storage-location/#what-types-of-data-are-stored-where) for more information.
+

docs/organization/data-storage-location/index.mdx

@@ -53,9 +53,19 @@ Here’s a list of the types of data that may be stored in the US.
 - Sentry applications
 - SSO, SAML, and SCIM metadata
 
-
 Metadata that lets Sentry identify an organization will be replicated out of the organization's data storage location to facilitate login, and backwards-compatible APIs. You can always confirm the location of your organization by viewing your organization's settings page.
 
+## Using Data Storage Location APIs
+
+To ensure that your API requests are only processed within your selected data storage location use the region specific domain for your data storage location:
+
+| **Data Storage Location**     | **API domain** |
+| ----------------------------- | -------------- |
+| United States of America (US) | us.sentry.io   |
+| European Union (EU)           | de.sentry.io   |
+
+For [data stored in the US](https://docs.sentry.io/organization/data-storage-location/#data-stored-in-us) your API domain should be `sentry.io`.
+
 ## Switching Data Storage Locations for Existing Organizations
 
 ### SaaS