docs(router): multiple Hive CDN endpoints (#7833)

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

packages/web/docs/src/content/router/configuration/supergraph.mdx

@@ -22,7 +22,7 @@ Load the Supergraph schema from [Hive Console](../../schema-registry) CDN.
 
 ### `endpoint`
 
-- **Type:** `string`
+- **Type:** `string` or `string[]`
 - **Required:** Yes
 - **Environment Variable:** `HIVE_CDN_ENDPOINT`
 
@@ -36,6 +36,32 @@ supergraph:
   # ...
 ```
 
+#### Multiple endpoints
+
+You can provide multiple endpoints as an array of strings. This allows the router to use fallback
+endpoints in case of a possible unavailability of the main CDN endpoint. The order matters; the
+router will always try to fetch the supergraph from the first endpoint, and if it fails, it will
+move on to the next one.
+
+```yaml {3} filename="router.config.yaml"
+supergraph:
+  source: hive
+  endpoint:
+    - https://cdn.graphql-hive.com/artifacts/v1/... # Main CDN endpoint
+    - https://cdn-mirror.graphql-hive.com/artifacts/v1/... # Fallback CDN endpoint
+  # ...
+```
+
+If you provide the endpoints using `HIVE_CDN_ENDPOINT` environment variable, separate them with a
+comma:
+
+```bash
+HIVE_CDN_ENDPOINT=https://cdn.graphql-hive.com/artifacts/v1/...,https://cdn-mirror.graphql-hive.com/artifacts/v1/...
+```
+
+> Learn more about
+> [CDN Mirrors in Hive Console](../../schema-registry/high-availability-cdn#cdn-mirrors).
+
 ### `key`
 
 - **Type:** `string`

packages/web/docs/src/content/router/supergraph.mdx

@@ -55,6 +55,19 @@ supergraph:
   poll_interval: 60s
 ```
 
+You can also provide fallback endpoints from `cdn-mirror-graphql-hive.com` in case of a possible
+unavailability of the main CDN endpoints, as shown below:
+
+```yaml {3-5} filename="router.config.yaml"
+supergraph:
+  source: hive
+  endpoint:
+    - https://cdn.graphql-hive.com/artifacts/v1/... # Use your Hive CDN endpoint here
+    - https://cdn-mirror.graphql-hive.com/artifacts/v1/... # Use your Hive CDN mirror endpoint here
+  key: hvABCD # Use your Hive CDN API key here
+  poll_interval: 60s
+```
+
 For additional configuration options, refer to the
 [`supergraph` API reference page](./configuration/supergraph).